Question

Find the common factors of :
(a) 20 and 28
(b) 15 and 25
(c) 35 and 50
(d) 56 and 120

Answer 1

(a)factors of 20 = 1,2,4,5,10,20
factors of 28 = 1,2,4,7,14,28
common factors = 1,2,4

(b)factor of 15 = 1,3,5
factors of 25 = 1,5,25
common factors = 1,5

(c)factors of 35 = 1,5,7,35
factors of 50 = 1,2,5,10,25,50
common factors = 1,5

(d)factors of 56 = 1,2,4,7,8,14,28,56
factors of 120 = 1,2,3,4,5,6,10,12,20,30,40,60,120
common factors = 1,2,4

Answer 2

Question (a):

Find the factors of 20:

20 = 1 x 20

20 = 2 x 10

20 = 4 x 5

Factors of 20 are 1, 2, 4, 5, 10 and 20

Find the factors of 28:

28 = 1 x 28

28 = 2 x 14

28 = 4 x 7

Factors of 28 are 1, 2, 4, 7, 14 and 28

Find the common factors:

Factors of 20 = 1, 2, 4, 5, 10, 20

Factors of 28 = 1, 2, 4, 7, 14, 28

Common factors are 1, 2, and 4

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Question (b):

Find the factors of 15:

15 = 1 x 15

15 = 3 x 5

Factors of 15 are 1, 3, 5 and 15

Find the factors of 25:

25 = 1 x 25

25 = 5 x 5

Factors of 25 are 1, 5 and 25

Find the common factors:

Factors of 15 = 1, 3, 5, 15

Factors of 25 = 1, 5, 25

Common factors are 1 and 5

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Question (c):

Find the factors of 35:

35 = 1 x 35

35 = 5 x 7

Factors of 35 are 1, 5, 7 and 35

Find the factors of 50:

50 = 1 x 50

50 = 2 x 25

50 = 5 x 10

Factors of 50 are 1, 2, 5, 10, 25 and 50

Find the common factors:

Factors of 35 = 1, 5, 7, 35

Factors of 50 = 1, 2, 5, 10, 25, 50

Common factors are 1 and 5

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Question (d):

Find the factors of 56:

56 = 1 x 56

56 = 2 x 28

56 = 4 x 14

56 = 7 x 8

Factors of 56 are 1, 2, 4, 7, 8, 14, 28 and 56

Find the factors of 120:

120 = 1 x 120

120 = 2 x 60

120 = 3 x 40

120 = 4 x 30

120 = 5 x 24

120 = 6 x 20

120 = 8 x 15

120 = 10 x 12

Factors of 120 are 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 30, 40 , 60 and 120

Find the common factors:

Factors of 56 = 1, 2, 4, 7, 8, 14, 28, 56

Factors of 120 = 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 30, 40 , 60, 120

Common factors = 1, 2, 4 and 8