🌀 What is Pi Symbol π? The Infinite Secret of Circles (2026)

Video: Math Antics – Circles, What Is PI?

The pi symbol (π) is the universal mathematical shorthand for the irrational constant representing the ratio of a circle’s circumference to its diameter, a number that never ends and never repeats. When you ask what is pi symbol π?, you are essentially asking for the key that unlocks the geometry of the entire universe, from the spin of a galaxy to the ripple of a pond.

Legend has it that the ancient Greek mathematician Archimedes spent his final moments scribling geometric proofs in the sand, completely oblivious to the invading Roman soldiers, all while chasing the elusive value of this very ratio. Today, we know that π stretches into infinity with over 62 trillion digits calculated so far, yet we still haven’t found a repeating pattern.

Key Takeaways

π is the ratio of a circle’s circumference to its diameter, approximately 3.14159.
It is an irrational and transcendental number, meaning its decimal expansion is infinite and non-repeating.
The symbol π was popularized by Leonhard Euler in the 18th century, derived from the Greek word for “periphery.”
Despite its infinite nature, 15 digits of π are sufficient for NASA’s most precise space calculations.
π appears everywhere in science, from quantum mechanics to signal processing, proving it is fundamental to the fabric of reality.

⚡️ Quick Tips and Facts
📜 The Ancient Origins: How Humanity Discovered the Pi Symbol π
🧮 Decoding the Math: What Does the Pi Symbol π Actually Represent?
🔢 The Infinite Sequence: Why the Pi Symbol π Never Ends or Repeats
📝 Pi Symbol π Copy and Paste: 10+ Digits for Your Projects
🖥️ How to Type the Pi Symbol π on Any Device (Windows, Mac, Mobile)
🎨 Pi in Pop Culture: From Movies to T-Shirts and Memes
🏫 Teaching the Pi Symbol π: Fun Activities for Students and Teachers
🌍 Pi Beyond Math: Real-World Applications in Engineering and Science
🏆 The Modern Quest: Supercomputers and the Race for Trillions of Digits
🎂 Celebrating Pi Day: History, Traditions, and the Best Pie Recipes
🧠 Common Myths and Misconceptions About the Pi Symbol π
✅ Conclusion
🔗 Recommended Links
❓ FAQ: Your Burning Questions About the Pi Symbol π Answered
📚 Reference Links

⚡️ Quick Tips and Facts

Before we dive into the infinite decimal expansion of the universe’s most famous constant, let’s get the lowdown on what makes the Pi symbol (π) so special. Whether you’re a student trying to pass a geometry test or an engineer debugging a Raspberry Pi robot, these nugets of wisdom are your cheat sheet.

The Golden Ratio of Circles: At its core, π is simply the ratio of a circle’s circumference to its diameter. No matter if the circle is the size of a coin or the orbit of Jupiter, that ratio is always π.
It Never Ends: π is an irrational number. This means its decimal representation goes on forever without repeating. You’ll never find a pattern like “123123123” hiding in there.
It’s Not Just Math: While it started in geometry, π pops up in physics, statistics, engineering, and even music. It’s the heartbeat of anything that waves, spins, or oscillates.
The “623” Mystery: Did you know the first six consecutive 9s in the decimal expansion of π start at the 762nd decimal place? It’s known as the Feynman point, named after physicist Richard Feynman who jokingly wanted to memorize them to end with “…9… and say ‘and so on’.”
Pi Day is Real: Celebrated on March 14 (3/14), this day is a global phenomenon for math lovers, complete with pie-eating contests and coding marathons.

For a deeper dive into how we use this constant in our own projects, check out our dedicated guide on the significance of pi right here at Why Pi™.

📜 The Ancient Origins: How Humanity Discovered the Pi Symbol π

Video: Why is the Symbol Pi Used?

You might think π was discovered by a guy in a toga with a compass, but the story is far more collaborative—and messy. The journey to understanding this constant spans thousands of years and multiple civilizations.

The Early Guessers

Long before the symbol π existed, ancient civilizations were trying to figure out the ratio.

The Babylonians (c. 190–160 BC): They used a value of 3.125, derived from the approximation $25/8$. Not bad for a civilization that didn’t have calculators!
The Egyptians (c. 1650 BC): The Rhind Mathematical Papyrus suggests they used a value of approximately 3.1605, calculated by squaring $8/9$ of the diameter.

The Greek Revolution

The real breakthrough came with the Greeks, who loved geometry almost as much as they loved philosophy.

Archimedes of Syracuse (287–212 BC): He was the first to rigorously calculate π using the method of exhaustion. By inscribing and circumscribing polygons around a circle, he proved that π lies between 3.1408 and 3.1429. He essentially trapped the number between two values, a technique that would define mathematics for centuries.

Enter the Symbol: William Jones and Leonhard Euler

For a long time, mathematicians used phrases like “the quantity which, when the diameter is multiplied by it, yields the circumference.” Talk about a mouthful!

William Jones (1706): The Welsh mathematician was the first to use the Greek letter π to represent this constant in his book Synopsis Palmariorum Matheseos. He likely chose it because “periphery” starts with ‘p’ in Greek (peripheria).
Leonhard Euler (1736): While Jones started it, Euler made it stick. By adopting the symbol in his influential works, π became the universal standard we use today.

Fun Fact: Before π, some mathematicians used the fraction π/δ to denote the ratio of the semiperimeter to the semidiameter. Imagine trying to type that in a modern code editor!

🧮 Decoding the Math: What Does the Pi Symbol π Actually Represent?

Video: Number Pi – π – Math for Kids – What is Number Pi?

So, you know it’s the ratio of circumference to diameter, but what does that really mean for the world around you? Let’s break down the math without the headache.

The Core Formula

The definition is elegantly simple:
$$ \pi = \frac{C}{d} $$
Where:

$C$ = Circumference (the distance around the circle)
$d$ = Diameter (the distance across the circle through the center)

If you measure a circle’s diameter and multiply it by π, you get the circumference. If you know the radius ($r$), the formula becomes $C = 2\pi r$.

Why “Irrational” and “Transcendental” Matter

You’ve probably heard these terms thrown around, but they have huge implications.

Irrational: π cannot be written as a simple fraction (like $2/7$ is just an approximation). Its decimal expansion is infinite and non-repeating.
Transcendental: This is the heavy hitter. π is not the root of any non-zero polynomial equation with rational coefficients.
The Consequence: This proves that “squaring the circle” (constructing a square with the same area as a given circle using only a compass and straightedge) is impossible. It’s a mathematical dead end that stumped geometers for 2,0 years.

The Uppercase vs. Lowercase Distinction

Don’t get confused by the capital Π.

Lowercase π: The constant 3.14159…
Uppercase Π: In mathematics, this denotes the product of a sequence (similar to how Σ denotes summation).
Example: $\prod_{i=1}^{n} x_i$ means $x_1 \times x_2 \times … \times x_n$.

Real-World Visualization

Imagine you are building a Raspberry Pi robot with a circular base. To program the wheels to move in a perfect circle, your code needs to know exactly how far the robot travels in one rotation. That distance is $2\pi r$. If you use 3 instead of 3.14159, your robot will drift off course after just a few rotations. Precision matters!

For more on how geometry applies to DIY electronics, check out our guide on DIY Electronics.

🔢 The Infinite Sequence: Why the Pi Symbol π Never Ends or Repeats

Video: The Pi Song (Memorize 100 Digits Of π) | SCIENCE SONGS.

Why does π go on forever? Why can’t we just write it down and be done with it?

The Nature of Irrationality

If a number is rational, its decimal expansion either terminates (like $0.5$) or repeats (like $0.3…$). π does neither.

Proof of Irrationality: Proven by Johann Lambert in 1768, the proof is complex, but the result is clear: π cannot be expressed as $a/b$ where $a$ and $b$ are integers.

The Normal Number Conjecture

Here’s a mind-bending thought: π is likely a normal number.

What does that mean? It means that every digit (0-9) appears with equal frequency, and every sequence of digits (like your birthday, or the text of this article converted to numbers) appears somewhere in the infinite string of π.
The Catch: We haven’t proven it yet. Statisticians like Yasumasa Kanada have run tests on trillions of digits, and so far, the digits look perfectly random.

The Feynman Point

As mentioned earlier, at the 762nd decimal place, there is a sequence of six 9s:
...9...
This is a statistical anomaly that makes π feel almost “too perfect” in its randomness.

Approximations: Good Enough for Most?

While we can’t write the exact value, we use approximations:

Approximation	Value	Accuracy	Use Case
3	3.0	Low	Rough estimates, mental math
2/7	3.1428…	~0.04% error	School geometry, quick calcs
35/13	3.1415929…	~0.08% error	Engineering, high precision
3.14159	3.14159	~0.05% error	Standard scientific use

Even NASA uses only 15 digits of π for their most precise calculations (like sending probes to the edge of the solar system). Using more digits than that wouldn’t change the result by the width of a hydrogen atom!

📝 Pi Symbol π Copy and Paste: 10+ Digits for Your Projects

Video: What Is Pi (π)? Is It Infinite?

Need the symbol π for your document, code, or social media post? We’ve got you covered. Whether you need the standard symbol or fancy mathematical variants, here is your ultimate copy-and-paste list.

Standard Pi Symbols

Standard Lowercase: π
Standard Uppercase: Π
Greek Small Letter Pi: π (U+03C0)
Greek Capital Letter Pi: Π (U+03A0)

Mathematical Variants (For LaTeX, Word, and Code)

Sometimes you need a bold or italic version for specific formatting:

Mathematical Bold Small Pi: 𝝅
Mathematical Italic Small Pi: 𝜋
Mathematical Sans-Serif Bold Small Pi: 𝝿
Mathematical Script Small Pi: 𝜋 (Note: Script styles vary by font)
Mathematical Double-Struck Small Pi: 𝛑 (Rare, but exists)

How to Use These in Code

If you are coding in Python or JavaScript, you usually don’t need to copy-paste the symbol if you just need the value.

Python: import math; print(math.pi)
JavaScript: Math.PI
LaTeX: \pi

However, if you are displaying the symbol in a web page, use the HTML entity:

π renders as π
π renders as π

Pro Tip: If you are working on a Raspberry Pi project with a display, ensure your font supports the Unicode character U+03C0. Most modern fonts do, but old-school terminal fonts might show a box or a question mark.

🖥️ How to Type the Pi Symbol π on Any Device (Windows, Mac, Mobile)

Video: The Best Explanation of Pi.

Stuck trying to type π on your keyboard? Don’t panic. Here is the definitive guide to getting that symbol on your screen, no matter what device you are using.

Windows PC

The classic Alt Code method is the fastest way.

Make sure Num Lock is on.
Hold down the Alt key.
Type 960 on the numeric keypad.
Release Alt.
Result: π
Note: If you don’t have a numeric keypad, this method won’t work. Try the Character Map or the Windows Emoji panel (Win + .).

Mac

Macs have a built-in shortcut that is incredibly convenient.

Hold down the Option key.
Press the p key.
Result: π
Alternative: Use the Character Viewer (Control + Command + Space) and search for “pi”.

Mobile (iOS and Android)

iOS (iPhone/iPad):

Go to the keyboard.
Tap the 123 button.
Tap the #+= button.
Long-press the p key (if available) or look for the Symbols tab. On some keyboards, you can add a Greek keyboard in Settings > General > Keyboard.

Android:

Switch to the symbols keyboard.
Look for the Greek or Math symbols tab.
If not found, long-press the p key on some Gboard configurations.

Linux

Compose Key: If you have a Compose key configured, press Compose, then p, then i.
Unicode Hex: Hold Ctrl + Shift + U, type 03c0, then press Enter.

For more tech tips and component reviews, visit our Electronic Component Reviews section.

🎨 Pi in Pop Culture: From Movies to T-Shirts and Memes

Video: The Pi Song 4.0 (Memorize 400 Digits Of π).

π isn’t just for nerds in lab coats. It has permeated our culture, appearing in movies, music, and even on your local coffee shop’s chalkboard.

Movies and TV

The Pi (198): Darren Aronofsky’s psychological thriller follows a mathematician obsessed with finding patterns in the stock market and the universe, centered around the number 216 (which is related to π in his delusion).
Star Trek: In “The Omega Glory,” Captain Kirk uses the value of π to prove he is from Earth, as the alien computer couldn’t compute it.
The Simpsons: The show has made numerous references, including an episode where Homer tries to calculate π and gets stuck on the 3.14159… loop.

Music

Kate Bush: Her song “Pi” features the lyrics “3.14159…” sung to the tune of a catchy pop melody.
Michael Blake: “The Pi Song” is a popular educational tune that helps students memorize the first few digits.

The “Indiana Pi Bill”

One of the most bizarre moments in history occurred in 1897 in Indiana. A doctor named Edwin Goodwin claimed to have “squared the circle” and proposed a bill to legally define π as 3.2.

The Outcome: The bill passed the Indiana House of Representatives but was stopped in the Senate by a mathematics professor who pointed out the absurdity. It was never signed into law.
The Lesson: Never let politicians define mathematical constants!

Memes and Merch

From “I love π” t-shirts to mugs that say “3.14”, the symbol is a staple of geek chic. It’s the ultimate symbol of the infinite, the mysterious, and the beautiful.

🏫 Teaching the Pi Symbol π: Fun Activities for Students and Teachers

Video: An Awesome History of π (Pi).

How do you make π exciting for a classroom? We believe in learning by doing. Here are some activities that turn abstract math into tangible fun.

1. The “Pie” Measurement Challenge

Goal: Prove that C/d = π.

Materials: Various circular objects (cans, plates, wheels), string, ruler.
Activity: Have students measure the circumference (using string) and the diameter of each object. Divide $C$ by $d$.
Result: They will all get a number close to 3.14. It’s a “wow” moment when the data aligns.

2. Buffon’s Needle Experiment

Goal: Estimate π using probability.

Materials: A sheet of paper with parallel lines, toothpicks.
Activity: Drop toothpicks randomly. Count how many cross a line.
Formula: $\pi \approx \frac{2 \times \text{Total Drops}}{\text{Crossings}}$.
Why it works: It’s a classic probability problem that connects geometry and statistics.

3. Pi Day Recitation Contest

Goal: Memorize digits.

Activity: Host a contest to see who can recite the most digits of π.
Record: The current Guinness World Record is held by Rajver Mena, who recited 70,0 digits in 2015.

4. Coding Pi with Raspberry Pi

Goal: Calculate π using code.

Activity: Use Python to calculate π using the Leibniz formula or the Chudnovsky algorithm.
Code Snippet:

import math
print(f"Calculated Pi: {math.pi}")

Extension: Visualize the convergence of the series on a graph.

For more educational resources and project ideas, explore our DIY Electronics category.

🌍 Pi Beyond Math: Real-World Applications in Engineering and Science

Video: The Pi Song 3.0 (Memorize 300 Digits Of π).

You might think π is confined to the classroom, but it’s the silent partner in almost every engineering feat you see.

Engineering and Construction

Cylindrical Structures: Calculating the volume of pipes, tanks, and silos requires π.
Gears and Wheels: The design of any rotating mechanism relies on the relationship between radius and circumference.
Electrical Engineering: Alternating Current (AC) signals are sine waves. The period of a sine wave is $2\pi$. Without π, we wouldn’t have the power grid as we know it.

Physics and Cosmology

Quantum Mechanics: The Heisenberg Uncertainty Principle involves $\hbar$ (h-bar), which is Planck’s constant divided by $2\pi$.
General Relativity: Einstein’s field equations include π in the curvature of spacetime.
Orbital Mechanics: Calculating the orbit of satellites and planets requires π to determine distances and velocities.

Statistics and Data Science

Normal Distribution: The famous Bell Curve formula includes the term $1/\sqrt{2\pi}$.
Signal Processing: Fourier transforms, which break down signals into sine waves, rely heavily on $2\pi$.

Why It’s Everywhere

π appears wherever there is circularity, periodicity, or wave-like behavior. From the ripples in a pond to the spin of an electron, π is the universal constant of cycles.

🏆 The Modern Quest: Supercomputers and the Race for Trillions of Digits

Video: Unveiling The Remarkable Discovery Of Pi By A Genius – Prepare To Be Amazed!

Why do we keep calculating more digits of π? Is there a point where we stop?

The Record Breakers

1989: The Chudnovsky brothers calculated over 1 billion digits.
2010: Alexander Yee and Shigeru Kondo reached 10 trillion digits.
2021: Emma Haruka Iwao used Google Cloud to calculate 62.8 trillion digits.
2024: The record continues to climb, now exceeding 10 trillion digits.

The Algorithms

How do they do it?

Chudnovsky Algorithm: The current gold standard. It produces about 14 correct digits per term.
BBP Formula: Allows the calculation of specific hexadecimal digits without computing the preceding ones.
Spigot Algorithms: Generate digits one by one, like water from a spigot.

The Purpose

Testing Hardware: Calculating π is a stress test for supercomputers. If a computer can calculate π to 10 trillion digits without error, it’s a reliable machine.
Mathematical Research: Scientists study the digits to test the Normal Number Conjecture and look for hidden patterns.
Cryptography: While not directly used for encryption, the algorithms developed for π calculation often have applications in number theory and cryptography.

Did you know? The calculation of π to such high precision is a benchmark for the performance of cloud computing platforms.

🎂 Celebrating Pi Day: History, Traditions, and the Best Pie Recipes

Video: Celebrate Pi Day with America’s 5 Favorite Pies.

March 14 is not just another Tuesday. It’s Pi Day!

The History

Origin: Celebrated since 198 by the Exploratorium in San Francisco.
Date: 3/14 (Month/Day) matches the first three digits of π.
Einstein Connection: March 14 is also the birthday of Albert Einstein, adding a double layer of genius to the day.

Traditions

Eating Pie: The pun is irresistible. Whether it’s apple, cherry, or a savory quiche, eating pie is the main event.
Reciting Digits: Competitions to see who can memorize the most digits.
Wearing Pi Shirts: Show off your love for math with a shirt that says “I’m a Pi-rate” or “3.14”.

Best Pi Day Recipes

Classic Apple Pie: A timeless favorite.
Pi-Shaped Cookies: Cut your dough into the shape of π.
Mathematical Pizza: Make a circular pizza and cut it into slices that represent fractions of π.

For more fun project ideas and community events, check out our Electronics Industry News section.

🧠 Common Myths and Misconceptions About the Pi Symbol π

Video: The Discovery That Transformed Pi.

Let’s clear up some confusion. There are a lot of myths floating around about π.

Myth 1: “π is exactly 2/7”

Fact: 2/7 is a convenient approximation, but it is not the exact value. The true value is irrational and infinite.

Myth 2: “π was discovered by Archimedes”

Fact: Archimedes calculated it with incredible precision, but he didn’t “discover” the concept. The Babylonians and Egyptians knew about the ratio long before him.

Myth 3: “We need trillions of digits for space travel”

Fact: NASA uses only 15 digits for their most precise calculations. Using more would be like measuring the distance to the moon with a ruler marked in millimeters when you only need centimeters.

Myth 4: “π is a random number”

Fact: While the digits appear random, they are generated by a deterministic formula. They are not truly random; they are just pseudorandom in their distribution.

Myth 5: “You can square the circle”

Fact: As proven by the transcendental nature of π, it is mathematically impossible to construct a square with the same area as a circle using only a compass and straightedge.

✅ Conclusion

So, what have we learned about the Pi symbol (π)? It’s far more than just a number you memorize for a geometry test. π is the universal constant that connects the circle to the cosmos. From the ancient Babylonians guessing its value to modern supercomputers calculating trillions of digits, humanity’s quest to understand π mirrors our quest to understand the universe itself.

Key Takeaways:

π is the ratio of a circle’s circumference to its diameter.
It is an irrational and transcendental number, meaning it never ends and never repeats.
It appears in physics, engineering, statistics, and music, proving that math is the language of nature.
While we can approximate it with 2/7 or 3.14, the true value is infinite.
The symbol π was popularized by Leonhard Euler in the 18th century.

Our Recommendation:
Whether you are a student, an engineer, or a curious mind, embrace π. Don’t just memorize the digits; understand the beauty of the constant. Use it to build, to calculate, and to explore. And next time you eat a pie, remember that you are celebrating a number that has fascinated humanity for millennia.

If you’re ready to put π to work, why not start a Raspberry Pi project? From calculating π to visualizing wave patterns, the possibilities are endless.

🔗 Recommended Links

Ready to dive deeper? Here are some of our top picks for books, tools, and resources to help you explore the world of π.

Books on Pi

“A History of Pi” by Petr Beckmann: A comprehensive look at the history and mathematics of π.
Check Price on Amazon
“The Joy of Pi” by David Blatner: A fun and engaging exploration of the number π.
Check Price on Amazon

Tools and Kits

Raspberry Pi 5 Kit: Perfect for running your own π calculation algorithms.
Shop Raspberry Pi on Amazon
Shop Raspberry Pi on Walmart
Raspberry Pi Official Website

Online Resources

Pi Symbol Copy and Paste: A comprehensive list of π symbols and codes.
Visit PiSymbol.net
Wolfram MathWorld: Detailed mathematical entries on π.
Visit Wolfram MathWorld

❓ FAQ: Your Burning Questions About the Pi Symbol π Answered

Are there any Raspberry Pi projects or tutorials that involve calculating or utilizing pi in a creative or innovative way?

Absolutely! The Raspberry Pi is a fantastic platform for exploring π.

Pi Calculation: You can write Python scripts to calculate π using the Leibniz formula or the Chudnovsky algorithm.
Visualization: Use libraries like Matplotlib to visualize the convergence of π series or to plot the digits of π as a spiral.
Robotics: If you are building a robot with circular wheels, you’ll need π to calculate the distance traveled per rotation.
Audio: Generate sine waves (which rely on $2\pi$) to create musical tones or sound effects.

For more project ideas, check out our DIY Electronics section.

What are some interesting facts and trivia about pi that I can learn more about while working on Raspberry Pi projects?

Feynman Point: The sequence of six 9s at the 762nd decimal place.
Normal Number: The digits of π appear to be evenly distributed, but this is unproven.
Buffon’s Needle: You can simulate this probability experiment on your Raspberry Pi to estimate π.
Pi Day: March 14th is a great day to run a π calculation marathon on your Pi.

How does the concept of pi relate to circular shapes and geometry in Raspberry Pi-based robotics and automation?

In robotics, π is essential for:

Odometry: Calculating the distance a robot travels based on wheel rotations.
Path Planning: Creating circular paths or arcs.
Sensor Calibration: Calibrating sensors that rely on angular measurements (like encoders).
Inverse Kinematics: Solving for joint angles in robotic arms, which often involve trigonometric functions of π.

Can I use Raspberry Pi to calculate and visualize pi to a high degree of accuracy?

Yes! While a Raspberry Pi won’t break the world record (that requires supercomputers), it can easily calculate π to millions of digits.

Python: Use the decimal module for high-precision arithmetic.
Visualization: Use Matplotlib or Plotly to create beautiful visualizations of the digits.
Performance: The Raspberry Pi 5 is fast enough to calculate millions of digits in a reasonable time.

What are some real-world applications of pi in science and engineering, and how can I explore them with Raspberry Pi projects?

Signal Processing: Use π in Fourier transforms to analyze audio or sensor data.
Physics Simulations: Simulate pendulum motion or wave propagation.
Astronomy: Calculate orbital periods or distances.
Engineering: Design gears, springs, or any circular component.

How is pi used in programming and coding, particularly with Raspberry Pi?

Trigonometry: Functions like sin(), cos(), and tan() use π for radians.
Graphics: Drawing circles, arcs, and curves in games or visualizations.
Data Analysis: Normal distributions and statistical models.
Constants: Most programming languages have a built-in constant for π (e.g., math.pi in Python).

What is the significance of pi in mathematics and computing?

Mathematics: π is a fundamental constant in geometry, trigonometry, calculus, and number theory.
Computing: It is used in algorithms, cryptography, and performance testing.
Universality: π appears in almost every branch of science, making it a unifying concept.

What is the pi symbol in math?

The pi symbol (π) is the lowercase Greek letter pi. It represents the ratio of a circle’s circumference to its diameter.

What does pi π represent?

π represents the constant ratio of a circle’s circumference to its diameter. It is approximately 3.14159.

What does a big pi symbol mean?

The uppercase Pi (Π) is used in mathematics to denote the product of a sequence (similar to how Σ denotes summation).

Why is it called π?

It is called π because it comes from the Greek word peripheria (periphery) or perimetros (perimeter), which relate to the circumference of a circle.

Read more about “Why is it called π?”

What is this symbol π?

This symbol is the Greek letter pi, used in mathematics to represent the constant 3.14159….

📚 Reference Links

Wikipedia: Pi – Comprehensive overview of the history, math, and culture of π.
Wumbo.net: Pi Symbol – Technical specifications and usage of the π symbol.
PiSymbol.net: Pi Symbol Copy and Paste – A collection of π symbols and codes for copying and pasting.
Raspberry Pi Foundation: Raspberry Pi Official Website – The official site for Raspberry Pi products and resources.
MIT: One Billion Digits of Pi – A text file containing the first billion digits of π.
NASA: Pi in the Sky – How NASA uses π in space exploration.