Ann picks a 4-digit number.
the first digit is not zero.
the 4-digit number is a multiple of 5
how many different 4-digit numbers could she pick?

How many 4 digit numbers are divisible by 5? This can be answered by thinking of the combinations of digits. For example, the first three digits could be anything from 100 to 999. There are 900 combinations, because 999-100 plus 1 (to count 999 in, subtracting counts the distance between) and numbers divisible by 5 end in a 5 or a 0, so 900 x2 for 2 combinations is 1800 numbers. Hope this helps!