Question

7. A five digit number has digit form a74b3.If it is divisib 3, which of the following is possible value of a + b ? ​

Answer 1

a + b must be a number in the sequence 1, 4, 7, 10, 13, etc.

Explanation:

7 + 4 + 3 + x = 3n

14 + x = 3n

x = 1, 4, 7, 10, etc.

a + b must be a number in the sequence 1, 4, 7, 10, 13, etc.