Mathematics for IGCSE & O level - Number (Section 1 - No. 2)
Identify a pair of numbers where their HCF is 1.
12 and 18
15 and 20
7 and 10
21 and 28
Explication
If two numbers have an HCF of 1, they are said to be relatively prime. 7 and 10 have an HCF of 1.