Question

I have an amount $9558.99, which I need to split between 4 people: 40%, 40%, 10%, 10% . (This is just an example where the problem surfaces)

When I calculate the fraction I get the following results, which all contain fractions of a penny, which is no good, because obviously I can’t give a person half a penny.

40%  $3823.5960
40%  $3823.5960
10%  $955.8990
10%  $955.8990
SUM  $9558.99

If I round up I get a penny over:

40%  $3823.60
40%  $3823.60
10%  $955.90
10%  $955.90
SUM  $9559.00 <-- 1 penny over

If I round down I get 3 penny less (again no suprise):

40%  $3823.59
40%  $3823.59
10%  $955.89
10%  $955.89
SUM  $9558.96 <-- 3 pennies under

So my question is what would be the correct approach to fairly divide the amount based on the percentages?

EDIT: This might not be a programming question per-se but I think it’s related to a programmer anyway.

Answer 1

Round up, and subtract the excessive penny(s) randomly.

To subtract randomly, pick n random people where n = number of leftover penny(s).

Intuitively speaking I believe that n will not be greater than 3 in this scenario.

(Alternatively, round down and spread remaining pennies randomly).