posted by kawal on .
Using digits 2, 3, 5, 6, 7 and 9, how many 3-digit numbers can be formed that are divisible by 5 such that the repetition of digits is not allowed?
herpity derp. If a number is divisible by 5, it must have five or 0 in its ones digit. Thus, five must be in the ones. 6 can be in 1 of 4 places. So can 5 and 4 and 3 and 2. So, the answer is....
Your number must be in the form
xx5, where the x can only be from 2,3,6,7 or 9
number of 3 digit numbers which are divisible by 5 are
5x4x1 = 20