the hcf of 495 and an unknown number is 3, so, how do I find out what is the unknown number?

Question

Ermmm help pls

Answer 1

495=3²×5×11, unknown number n=3m where m cannot be any of the prime factors of 495.

So the smallest value for n=3×2=6, because 2 is not a factor of 495.

The HCF of 6 and 495 is 3.

The next highest number is 3×7=21, because 7 is not a factor of 495.

The HCF of 21 and 495 is 3.

The next value for n=3×11=33, then 39, 3×17=51, 3×19=57, and so on avoiding anything containing a prime factor of 495.