How to find the hcf and the lcm of numbers using prime factorization. lcm
30 and 12.

hcm
12 and 20

Below in bold.

Step-by-step explanation:

30 = 2 * 3 * 5

12 = 2 * 2 * 3

Note that 2 and 3 are common to both factors

so the HCF = 2*3 = 6.

Only one 2 and one 3 of the duplicates are included in the LCM:

so the LCM = 2 * 3 * 2 * 5 =  60

20 = 2 * 2 * 5

12 = 2 * 2 * 3

HCF = 2 *2 = 4

LCM = 2*2*3*5 = 60.