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GATE | Sudo GATE 2020 Mock III (24 January 2019) | Question 8

  • Last Updated : 22 Jan, 2020

A 4-digit number of the form aabb is a perfect square. What is the value of a – b ?
(A) 3
(B) 2
(C) 1
(D) 4

Answer: (A)

Explanation: A number of the form aabb has to be a multiple of 11.
So, it is the square of either 11 or 22 or 33 or…so on up to 99.

882 = 7744 

This is the only solution possible.
Most of these trial and error questions need to be narrowed down a little bit before we can look for the solution.
That narrowing down is critical. In this case, we should look for multiples of 11.

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Hence the answer is “3”.

Option (A) is correct.

Quiz of this Question

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