A number consists of two digits. If the digits interchange places and the new number is added to the original number, then the resulting number will be divisible by :  Choose the correct choice from the following answers:
A) 3  B) 5  C) 9  D) 11  E) 13
Solution   Let the ten's digit be x and units digit be y. Then, number = 10x + y.   Number obtained by interchanging the digits = 10y + x.   ∴ (10x + y) + (10y + x) = 11 (x + y), which is divisible by 11.   Answer 11
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A number consists of two digits. If the digits interchange places and the new number is added to the original number, then the resulting number will be divisible by :