Download 12. Prime Factors

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Foundation Level
12. Prime Factors
Do not use a calculator
Exercise 1
The prime factors of a number can be found by using a tree diagram. The example below shows
how to find the prime factors of 36. In the same way find the prime factors of the other numbers.
44
36
12
22
2
90
210
34
3
4
2
3
68
2
Exercise 2
Write down all the factors of the following numbers.
1) 15
2) 20
3) 24
6) 40
7) 45
8) 60
11) 90
12) 100
13) 120
4) 30
9) 71
14) 130
Exercise 3
Express the following numbers as products of their prime factors.
1) 150
2) 160
3) 200
4) 210
6) 675
7) 945
8) 1715
9) 1155
11) 1680
12) 1404
13) 1260
14) 2376
5) 32
10) 84
15) 150
5) 260
10)1035
15) 1540
Exercise 4
Express the following numbers as products of their prime factors.
In each case state the smallest whole number it has to be multiplied by to produce a perfect
square.
1) 12
2) 18
3) 180
4) 80
5) 162
6) 252
7) 343
8) 468
9) 608
10) 980
11) 600
12) 360
13) 300
14) 192
15) 1850
Exercise 5
Calculate the largest odd number that is a factor of each of the following.
1) 108
2) 180
3) 200
4) 271
6) 504
7) 588
8) 720
9) 780
11) 1248
12) 1200
13) 2160
14) 2520
5) 294
10) 468
15) 3920