Question

abc is a three digit number such that a + c = 4 . Sum of abc and the number obtained after reversing the digits is 504. Find the value of 6 multiplied by b.

• A. 36
• B. 30
• C. 105
• D. 115

Answer 1

The correct option is B 30

General form of 3-digit number abc = 100a + 10b + c
Number obtained by reversing its digits = cba
General form of cba = 100c + 10b + a

abc + cba
= 100a + 10b + c + 100c + 10b + a
= 101a + 20b + 101c
= 101(a + c) + 20b
= 101 x 4 + 20 b
= 404 + 20b

Given 404 + 20 b = 504
20b = 504 - 404 = 100
b = 5

Therefore, 6 $\times$ 5 = 30