# Approximations for pi The number $\pi$, which occurs in the formulae for the [[circumference]] and [[area]] of a [[circle]], is [[irrational]]. It therefore cannot be written as a fraction of integers, but there are such fractions that are considered to be good approximations for $\pi$. | Approximation | Decimal | |:-------------:|:--------| | $\pi$ | $3.141592653589793$ | | $\frac{22}{7}$| $3.142857142857143$ | | $\frac{355}{113}$ | $3.1415929203539825$ | category: circle theorems