Find the HCF and LCM of 12, 15, 18, 27.

Prime factorisation:

$12=2 \times 2 \times 3=2^{2} \times 3$

$15=3 \times 5$

$18=2 \times 3 \times 3=2 \times 3^{2}$

$27=3 \times 3 \times 3=3^{3}$

Now,
HCF = Product of smallest power of each common prime factor in the number
= 3
LCM = Product of greatest power of each prime factor involved in the number

$=2^{2} \times 3^{3} \times 5=540$