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# What is pi?

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### Quick Answer

**Pi is the ratio of a circle's circumference to its diameter.** The number pi, symbolized by a Greek letter, has a constant value that approximately equals 3.14. The distance around any circle when divided by its diameter always gives this exact result.

This constant is commonly used to solve the area of a circle, with the formula "pi r^2“ or the product of pi and the square of the length of the radius. Pi is an irrational number, which means it cannot be expressed as a common fraction, and it has an infinite decimal representation without any repeating pattern. The rounded version of pi is accepted for general computations. Pi up to 20 decimal digits is 3.14159265358979323846.

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Q:
## Why does pi not have units?

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Full Answer >**Pi does not have units because it is a number, not a measurement.**However, pi is sometimes treated like a unit when referring to angle measurements because the actual unit, radians, is a length divided by length and is therefore dimensionless.Filed Under: -
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## Is Pi rational?

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Full Answer >**Pi is not a rational number.**It is considered irrational. A rational number is able to be written as a fraction with integers for both the numerator and denominator.Filed Under: -
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## Is pi a real number?

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Full Answer >**Pi is a real number, as all numbers that exist on a number line are real.**Real numbers include all rational and irrational numbers; pi is defined as an irrational number.Filed Under: -
Q:
## Is pi a rational number?

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Full Answer >**Pi is an irrational number, so named because it cannot be expressed as the ratio of two integers.**The decimal representation of an irrational number never ends or falls into a permanently repeating pattern.Filed Under: