Finding the smallest positive integer with prime factors.

First I would like to make it clear that I'm not asking this to help with my school work, as I don't go to school and I'm self-studying. So I would appreciate it if people would help me.

So I just started doing some past examination questions and there are a few questions that I'm not sure if I'm using the right method as it took me a long time to finish them.

Example:

The numbers 168 and 324, written as the products of their prime factors, are 168 = 2^3 x 3 x 7, 324 = 2^2 x 3^4.

Find

the smallest positive integer value of n for which 168n is a multiple of 324.

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Expressed as the product of prime factors, 198 = 2 x 3^2 x 11 and 90 = 2 x 3^2 x 5. Use these results to find

the smallest integer, k, such that 198k is a perfect square.

Question ens.

For the second question, I don't even know how to solve it, as my book didn't really explain it fully.