Pi (letter) facts for kids
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Quick facts for kids Greek alphabet |
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|---|---|---|---|
| Αα | Alpha | Νν | Nu |
| Ββ | Beta | Ξξ | Xi |
| Γγ | Gamma | Οο | Omicron |
| Δδ | Delta | Ππ | Pi |
| Εε | Epsilon | Ρρ | Rho |
| Ζζ | Zeta | Σσ | Sigma |
| Ηη | Eta | Ττ | Tau |
| Θθ | Theta | Υυ | Upsilon |
| Ιι | Iota | Φφ | Phi |
| Κκ | Kappa | Χχ | Chi |
| Λλ | Lambda | Ψψ | Psi |
| Μμ | Mu | Ωω | Omega |
| Other letters | |||
| Ϝϝ | Digamma | Ϟϟ | Koppa |
| Ϛϛ | Stigma | Ϡϡ | Sampi |
| Ͱͱ | Heta | Ϸϸ | Sho |
| Ϻϻ | San | ||
Pi (written as Π for uppercase and π for lowercase) is the sixteenth letter of the Greek alphabet. It makes a "p" sound, just like the "p" in "pizza." The ancient Greeks used it, and it's still used in Modern Greek today.
In the system of Greek numerals, which was how Greeks wrote numbers using letters, Pi had a value of 80. Over time, letters from the Greek alphabet influenced other alphabets. For example, the Roman letter P and the Cyrillic letter П both came from Pi.
Contents
Pi in Mathematics
Pi is super famous in mathematics, but it's used in two different ways:
The Mathematical Constant Pi (π)
When you see the lowercase π in math, it almost always means the special number known as the mathematical constant pi. This number is about 3.14159, but it actually goes on forever without repeating! It's also sometimes called Archimedes' constant, named after the famous ancient Greek mathematician.
This constant is incredibly important because it describes the relationship between a circle's circumference (the distance around it) and its diameter (the distance across it, through the center). No matter how big or small a circle is, if you divide its circumference by its diameter, you'll always get pi!
- Circumference = π × diameter
- Area of a circle = π × radius × radius (or πr²)
Pi helps us calculate things like the area of a circle or the volume of a sphere. It pops up in many areas of science and engineering, from understanding waves to designing rockets!
The Pi Product Operator (Π)
The uppercase Π is used in mathematics as a symbol for a "product." A product means multiplying numbers together. It works a bit like the summation symbol (Σ), which means adding numbers together.
For example, if you see something like Failed to parse (Missing <code>texvc</code> executable. Please see math/README to configure.): \Pi_{i=1}^5 i , it means you multiply all the numbers from 1 to 5: 1 × 2 × 3 × 4 × 5 = 120. This is also known as 5! (five factorial). So, the uppercase Pi tells you to multiply a series of numbers.
Related Pages
Images for kids
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A robot friend, ready to learn about Pi!
