If a nine-digit number 985x3678y is divisible by 72, then the value of (4x – 3y) is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 4
If a number is divisible by 72 it must be divisible by 8 and 9
985x3678y is divisible by 72.
The last 3 digits of 78y must be divisible by 8:
⇒ Then the possible value of y is 4
For divisibility by 9:
⇒ 9 + 8 + 5 + x + 3 + 6 + 7 + 8 + 4 must be divisible by 9
⇒ 50 + x must be divisible by 9
⇒ Possible value of x is 4
Hence, (4x - 3y) = 4 × 4 – 3 × 4 = 16 - 12 = 4