How many 4 digit multiples of 5 can be form d using the digits, 1,2,5,7,9,0 if repitions are not allowed?
clearly the last digit must be 0 or 5
The 1st digit cannot be zero.
So, there are
1st digit 5: 1*4*3*1 = 12
last digit 5: 4*4*3*1 = 48
last digit 0: 4*4*3*1 = 48