What will be the greatest number 32a78b, which is divisible by 3 but NOT divisible by 9? (Where a and b are single-digit numbers)
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 329784.
A number is divisible by 3 if the sum of its digits is divisible by 3
A number is divisible by 9 if the sum of its digits is divisible by 9
The sum of the digits = 3 + 2 + 7 + 8 + a + b = 20 + a + b
If a = 9 and b = 4 then, total sum = 20 + 9 + 4 = 33
33 is divisible by 3 but not divisible by 9
Therefore, the greatest number that satisfies the conditions is 329784.