91Ó°ÊÓ

In any expression or equation, the variable is an unknown quantity. It may be any alphabet or any special symbol.

Perfect squares always have an odd number of factors whereas non perfect squares always have an even number of factors.

$n=p_1^{a1}·p_2^{a2}\mathrm{...}{p}_r^{a_r}$

The first thing you can say just by looking at the question is that the answer will be a perfect square. Perfect squares always have an odd number of factors whereas non perfect squares always have an even number of factors.

There is a formula that gives you the number of factors of a positive integer > 1 from its prime factorization. If you aren’t familiar with the formula, you can always try the perfect squares$2^2,3^2,…,2^2,3^2$,…,until you come to the right one. It will be$8^2=64$$2^6=64.$

The factors of 64 are, 1, 2, 4, 8, 16, 32, and 64.

So, 64 is the least whole number with exactly 7 factors including 1 and itself.