what is the smallest number that 54 can be multiplied by to give a perfect square?

Answer 1

all perfect squares have pairs of equal factors

e.g. 400
= 2x2 x 10x10

54 = 2 x 3 x 3 x 3
so we need another 2 and another 3

so the smallest number to be multiplied by 54 so it becomes a perfect square is 6

check:
6x54 = 324 = 18^2