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  1. A number consists of two digits. If the number formed by interchanging the digits is added to the original number, the resulting number (i.e. the sum) must be divisible by
    1. 11
    2. 9
    3. 5
    4. 3
Correct Option: A

Let the number be 10a + b .
After interchanging the digits, the number obtained = 10b + a.
According to the question,
Resulting number = 10a + b + 10b + a
Resulting number = 11a + 11b
Resulting number = 11 (a + b)
which is exactly divisible by 11.



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