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Solution



To find:
    • The option which is not the square of any integer.

Approach and Working:
If a number x is a square of a number and if the prime factorization of x = \(P_1^a×P_2^b×P_3^c\), the powers a, b, and c must be even. If we have more prime factors, all the powers must be even.
    • Thus, if the number is even, the only even prime number that can contribute is 2.
      o Thus, the possible units digit for even numbers that are squares = \(2^2 = 4, 2^4 = 16\) (units digit = 6) and repeats later on.
    • Since option D has the units digit of 2, it cannot be a perfect square.

Hence the correct answer is Option D

Answer: D
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Bunuel
Which one of the following numbers is not a square of any integer?

(A) 17,956
(B) 18,225
(C) 53,361
(D) 63,592
(E) 64,009
Solution:

Recall that the units digit of a perfect square must be 0, 1, 4, 5, 6, or 9. So 63,592 can’t be a perfect square.

Answer: D
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