Highest Common Factor

We have seen how division can be simplified by finding factors common to the number of counters and boards and cancelling that factor.

In Division and Factors we saw that

can be simplified tousing the common factor of 9

The higher the common factor the smaller are the numbers left to divide.

A puzzle is to find the highest possible common factor to the two numbers.
The solution is to split the two numbers into prime factors and list those they have in common.

For example finding the HCF of 54 and 18 




If necessary rearrange the order of the prime factor cards and pair the factors that belong to each number




Multiply the common factors together

to find the product of these numbers.

Eighteen is the Highest Common Factor (HCF) of Fifty Four and Eighteen.

54 = 18 x 3
18 = 18 x 1


Using Eighteen as the highest common factor gives the same result as

which gives the same results as which gives the same result as

Record

Maths