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Is pi a repeating decimal?

Published in Mathematics 2 mins read

No, pi is not a repeating decimal.

Pi (π) is an irrational number, which means it cannot be expressed as a fraction p/q, where p and q are integers and q ≠ 0. Its decimal representation is non-terminating (it goes on infinitely) and non-repeating (the digits do not fall into a repeating pattern).

Understanding Repeating Decimals

A repeating decimal, also known as a recurring decimal, has a block of digits that repeats infinitely. For example:

  • 1/3 = 0.3333... (the digit 3 repeats)
  • 1/7 = 0.142857142857... (the block "142857" repeats)

Repeating decimals can always be expressed as fractions.

Why Pi is Different

Pi, on the other hand, has a decimal expansion that continues infinitely without any repeating pattern. Its approximate value is 3.14159265359..., but this is just a truncated representation. The digits continue indefinitely in a seemingly random order.

Key Characteristics of Pi

  • Irrational: Cannot be expressed as a fraction of two integers.
  • Transcendental: Not the root of any non-zero polynomial equation with rational coefficients. (This is a stronger condition than being irrational).
  • Non-terminating: Its decimal representation goes on forever.
  • Non-repeating: Its decimal representation does not have a repeating pattern.

Because pi is a non-repeating, non-terminating decimal, it is classified as an irrational number.

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