YOU ARE LEARNING:
Factors are each of the numbers which we can divide another number by, and get a whole number.
A factor perfectly divides a number, leaving a whole number with no remainder.
When you divide 16 by any of these numbers, the answer is whole.
What is 16÷1?
What is 16÷2?
What is 16÷4?
These are all factors of 16
Similarly, we can multiply pairs of these together to regenerate 16. For example, 2×8=16 and 1×16=16.
Which of the following is NOT a factor of 15?
It's useful to identify factors of a number and list them in order without skipping any.
Let's find the factors of 80
We could try out random numbers
But this could take a while, and we could miss a factor out by accident.
We need a more systematic method
Let's find factor pairs of 80, using multiplication facts, starting with 1.
What, multiplied by 1, gives the answer 80?
The first multiplication is 1×80
Since both numbers multiply together to make 80 (and as a result, they both also divide 80 to give a whole number), they are both FACTORS.
What, multiplied by 2, gives 80?
We have 1,2,40,80 as factors
Let's keep going systematically to find all the factors.
Does 80 divide by 3 to give a whole number?
3 is not a factor
It can't divide 80 to leave a whole number.
4,5,8 are also factors
Each of these numbers divide 80 to leave a whole number.
Is 9 a factor of 80?
9 isn't a factor
We have all the factors!
Let's try listing all the factors of 24.
Start by dividing by 1
We know a multiplication fact is 1×24
Next, try dividing 24÷2.
Is 5 a factor? (Yes/No)
We have them all!
6 is the next number we'd try, and it's already in the list. The factors of24 are:
What are ALL the factors of 10?
If two numbers share a factor, this is known as a common factor.
For example, let's look at the factors of 12 and 15
List all the factors of 12
List all the factors of 15
You will notice that both numbers share the factor of 1
But this is not the only common factor.
Other than 1, what other factor is shared by the two numbers?
12 and 15 have two common factors
Since 1 and 3 are factors of both numbers, they are common factors.
Find a common factor of 32 and 40.