If 5 A × A = 399, then the value of A is


According to the question


A x A = 9


The one’s place in the product of A and A is 9


A is the number whose multiplication with itself gives a two digit number having 9 in it’s one’s place.


Hence A = 7 because A x A = 49 and one’s place of 49 is 9


Option (c) is correct.

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