UPSC CDS I 2019 Math Paper

Solution.
If the number is divisible by 9 the sum of all its digit is divisible by 9
4+7+9+8+6+5+A+B = 39 + A + B is divisible by 9
Possible values of B are 1,3,5,7,9 as it is given that last digit is odd
For B= 1, A=5
For B = 3 A= 3
For B= 5 , A = 1
For B = 7, A = 8
For B = 9, A= 6