0, if we're talking natural numbers or integers. There isn't one if we're talking real numbers. Simple proof: Assume x is the largest number smaller than 1. (

0, if we're talking natural numbers or integers. There isn't one if we're talking real numbers. Simple proof: Assume x is the largest number smaller than 1. (x + 1)/2 is a number larger than x but smaller than 1. Our assumption that x is the largest number smaller than 1 must be wrong. QED.