If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.

Find the sum of all the multiples of 3 or 5 below 1000.

Solution:
Function Prob001() As Integer
For k As Integer = 3 To 999
If k Mod 3 = 0 OrElse k Mod 5 = 0 Then Prob001 += k
Next
End Function

Summary:
Easy-peasy.