Hey guys

Having a little bit of a math problem, i need a way in blue prints to take a number say 19 split that number in to 2 numbers of 10 and 9, but the number 19 could be anything 28, 20, 87 any thing so how can i make sure when i split the numbers up is does it by as close to half as possible without getting decimal points or remainders?

i know this is a bit of an odd question so if anyone needs anymore details please ask

thanks guys