Find the HCF of 75 and 90 prime factorisation

Prime factorization of 75:
$75=3\times 5^2$

Prime factorization of 90:
$90=2\times 3^2\times 5$

To find the HCF, we need to identify the common prime factors and multiply them together.

Common prime factors: $3$ and $5$

$HCF=3\times 5=15$

Therefore, the HCF of 75 and 90 is 15.