What is the value of a so that the seven-digit number

Solution

To find a so that 4645a52 is divisible by 72, check both conditions: 1. Divisibility by 8: Last three digits a52 must be divisible by 8. =052 (divisible by 8) =152 (not divisible by 8) =252 (not divisible by 8) =352 (divisible by 8) 2. Divisibility by 9: The sum of digits 26 + a must be divisible by 9. =26+0=26 (not divisible by 9) =26+1=27 (divisible by 9) =26+2=28 (not divisible by 9) =26+3=29 (not divisible by 9) so,a =1.