Question

The number X4531Y, where X and Y are single-digit numbers, is divisible by 72. Then X - Y is equal to:

• A. 5
• B. 7
• C. 8
• D. 1

Answer 1

The correct option is D 1

If a number is divisible by 72, it is divisible by 8 and 9. To be divisible by 8, the number formed by the last three digits should be divisible by 8. Therefore, 31Y should be divisible by $8⟹Y=2$. To be divisible by 9, the sum of the digits of the number should be divisible by $9⟹X=3$. Therefore, $X-Y=1.$