How many fourdigit numbers are there formed from the digits

How many four-digit numbers are there formed from the digits 1, 2, 3, 4, 5 (with possible repetition) that are evenly divisible by 4?

Solution

Any number (regardless of number of digits) with the last 2 digits that are divisble by 4 is divisble by 4.

then number is:

xx12, xx24, xx32,xx44, xx52 . that is 5 possibilities for last two digits.

For the hundredth place and thousand place digit have 5 possibilities.

Hence the total numbers = 5*5*5= 125