Exercise 13.
For how many three digit numbers (100 to 999) is the sum of the digits even? (For example, \(343\) has an even sum of digits: \(3+4+3 = 10\) which is even.) Find the answer and explain why it is correct in at least two different ways.
For how many three digit numbers (100 to 999) is the sum of the digits even? (For example, \(343\) has an even sum of digits: \(3+4+3 = 10\) which is even.) Find the answer and explain why it is correct in at least two different ways.