2 and 12
You cannot. The numbers 2 and 12 have hcf = 2 and LCM = 12 The numbers 4 and 6 also have hcf = 2 and LCM = 12 So if you just knew the hcf and LCM you would not know which of the two was the required pair.
2 and 12
2 and 12
3 and 12
6 and 4
How about 4 and 6
The GCF is 2.
4 and 6
6 and 36 12 and 18
The HCF of both numbers is 2
The GCF is 2.