Question 42956
The easiest way to do this is to sum up all the two digit numbers and subtract those divisible by 5...
The sum of the numbers 10 to 99 = (90/2)(10+99) = 4905
The sum of the numbers 10, 15, 20, ..., 95 = (20/2)(10+95) = 1050
4905 - 1050 =
3855