How many 3 digit numbers have a sum of 10?

To find how many three-digit numbers have a sum of 10, we can denote the digits as (a), (b), and (c), where (a) is the hundreds place, (b) is the tens place, and (c) is the units place. Since (a) must be between 1 and 9 (inclusive) and (b) and (c) can be between 0 and 9, we need to solve the equation (a + b + c = 10) with the constraints on (a). By systematically counting the valid combinations, we find there are 36 three-digit numbers where the sum of the digits equals 10.