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