Page 8 - Math Smart - 7

^ RECALL Factors and prime numbers

d List the first 3
multiples of each of
Investigate!
the following:
PAIR WORK
a) 15 b)20
Use the numbers in the box. Find all the number pairs that give the products:
c)25 d)50 1. X __ = 24

Q List the first 10 prime 2. X __ = 24
numbers. 3. X __ = 36
8
Q Draw a dot array to 4. X __ = 8
show the factors for 5. X = 30
the number 42.

Factors

A factor is a number which divides into another number exactly without leaving
In other words, factors of a
a remainder. For example, 6 and 4 are factors of 24. However, 6 and 4 are not the
number, when multiplied
only factors of 24.
together, would give you
the number itself as the 1 X 24 = 24
product.
2 X 12 = 24
3 X 8 = 24
4x6 = 24 So, the factor list for 24 is 1, 2, 3, 4, 6, 8, 12,24

Example 1

5 is not a factor of 36 Write a factor list for 36.
because it cannot divide Step 1: Make a list of the pairs of numbers that give a product of 36.
36 exactly.
1 X 36 = 36
2 X 18 = 36
Although 6 x 6 = 36, we I 3 X 12 = 36
only write the number 6 I 4 X 9 = 36
once in the factor list. We ; 6 X 6 = 36
do not repeat them.
Step 2: Write the factors of 36 in an Increasing order.
The factor list for 36 is 1, 2, 3, 4, 6, 9, 12, 18 and 36.

UNIT 1 Factors, Multiples and Primes