In a three-digit number, the hundreds digit is greater than 5, the tens digit is greater than 4 but less than 8, and the units digit is the smallest prime number. How many three-digit numbers satisfy all of these conditions?
We have 4 possibilities for the hundreds digit [6, 7, 8 or 9], 3 posibilities for the tens digit [ 5, 6 , 7 ] and the units digit is 2 [ the smallest prime]
So....the number of 3-digit numbers satisfying these conditions is :
+612 
