This activity is all about finding the highest common factors of numbers.

The factors of 42 are 1, 2, 3, 6, 7, 14, 21 and 42.

The factors of 28 are 1, 2, 4, 7, 14 and 28.

Some of these factors appear in both lists and these are the common factors of 42 and 28. 

They are: 1, 2, 7 and 14

But 14 is the greatest or the highest common factor (HCF) of 42 and 28.

Let's have a go at the questions now.