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Investigation
25 has exactly three factors:
1, 5, and 25
Find other numbers with exactly three factors.
Number
Factor 1
Factor 2
Factor 3
25
1
5
25
What do you notice about numbers with exactly 3 factors?
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Please circle (1 is not at all and 4 is very much)
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Comments
Partner
1 2 3 4
1 2 3 4
1 2 3 4
Student
1 2 3 4
1 2 3 4
1 2 3 4
1
1
2
3
4
2
3
4
Year 8
Half Term 1
Multiples, Factors and Primes
Name
Maths Class
Maths Teacher
Maths Partner
Date
A Few Reminders
A multiple is another name for the numbers in a times
table.
The lowest common multiple (LCM) of two numbers is
the lowest number that appears in both sets of
multiples.
Example - 12 is the lowest common multiple of 4 and 6
because 12 is the lowest number that is in the 4 and 6
times table.
A Factor goes into another number exactly.
The highest common factor (HCF) of two numbers is the
largest number that will divide exactly into both
numbers.
Example - The highest common factor of 8 and 12 is 4
because 4 is the largest number that will divide into
exactly into 8 and 12.
A prime factor is a factor that is prime.
Example - 7 is a prime factor of 14 because 7 is prime
and divides exactly into 14
Prime Factor Finder
You need 2 different coloured pencils and paper to keep score
Take turns to:
 Choose a number from the shaded boxes and cross it out.
 Shade all its prime factors in the main grid in your colour.
Add up all the numbers that you have coloured at the end.
The winner is the one with the biggest total.
Example – if you choose 18 you must shade 3, 3 and 2 because
3 x 3 x 2 = 18
20 12 40 24 27 16 48 100 18 25 80 70
2
3
2
7
2
3
5
5
2
2
2
3
2
2
2
3
5
3
2
2
2
2
5
5
2
2
2
2
2
2
Use the space below to record your sets
2
2
5
3
5
2
5
3
3
3
2
2
2
2
5