Which of the following numbers is exactly divisible by 24 ?

Answer: Option D

We have 24 = 3 × 8, where 3 and 8 are co-primes
Clearly,
718 is not divisible by 8. So, 35718 is not divisible by 8
810 is not divisible by 8. So, 63810 is not divisible by 8
804 is not divisible by 8. So, 537804 is not divisible by 8
736 is divisible by 8. So, 3125736 is divisible by 8
Also, sum of its digits = (3 + 1 + 2 + 5 + 7 + 3 + 6) = 27, which is divisible by 3
So, 3125736 is divisible by 3 also.
Hence, it is divisible by 24.