Claim: Pi is a number.

This article gives a mathematical definition . For a more accessible article see Decimal .   A decimal representation of a non-negative real number r is an expression in the form of a series , traditionally written as a sum   where a0 is a nonnegative integer , and a1 , a2 , ... are integers satisfying 0 ≤ ai ≤ 9 , called the digits of the decimal representation . The sequence of digits specified may be finite , in which case any further digits ai are assumed to be 0 . Some authors forbid decimal representations with a trailing infinite sequence of `` 9 `` s.  This restriction still allows a decimal representation for each non-negative real number , but additionally makes such a representation unique .  The number defined by a decimal representation is often written more briefly as   That is to say , a0 is the integer part of r , not necessarily between 0 and 9 , and a1 , a2 , a3 , ... are the digits forming the fractional part of r.   Both notations above are , by definition , the following limit of a sequence :  .