Which of the following numbers is divisible by 11?

Take the alternating sum of the digits in the number, read from left to right. If that is divisible by 11, so is the original number.


A. 1011011


Sum = 1 – 0 + 1 – 1 + 1 – 1 + 1 = 2


Since, 2 is not divisible by 11, 1011011 is not divisible by 11.


B. 1111111


Sum = 1 – 1 + 1 – 1 + 1 – 1 + 1 = 1


Since, 2 is not divisible by 11, 1011011 is not divisible by 11.


C. 22222222


Sum = 2 – 2 + 2 - 2 + 2 – 2 + 2 - 2 = 0


Since, 0 is divisible by 11, 22222222 is divisible by 11.


D. 3333333


Sum = 3 – 3 + 3 – 3 + 3 – 3 + 3 = 3


Since, 3 is not divisible by 11, 3333333 is not divisible by 11.

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