Page 79 - ICSE Math 4

Example 2: Is 9 a factor of 360? 40
Solu on: 9 is a factor of 360 since it divides 360 exactly 9 360
without leaving any remainder. –36
00
9 × 40 = 360
– 00
So, both 9 and 40 are the factors of 360.
00 Remainder
Common Factors
Remember
Common factors are the factors that are common to
The largest factor that is
two or more numbers. common to all the given

To fi nd the common factors of two or more numbers, numbers is called the highest
common factor or H.C.F. of
find the factors of each number and then iden fy the
the given numbers.
common factors among them.

Example 3: Find the common factors of 6 and 18.
Mental Maths
Solu on: Factors of 6: 1 , 2 , 3 and 6 .
Write True or False.
Factors of 18: 1 , 2 , 3 , 6 , 9 If 6 × 4 = 24, 24 × 2 = 48, then
and 18. (a) 6 is a factor of 48.

So, the common factors of 6 and (b) 4 is a factor of 6.
18 are 1, 2, 3 and 6. (c) 24 is a factor of 48.
(d) 2 is a factor of 24.

Exercise 7.1

1. Write any fi ve factors of the following numbers.

(a) 28 (b) 48 (c) 64 (d) 81 (e) 112
(f) 78 (g) 148 (h) 196 (i) 200 (j) 264

2. Encircle the factor(s) of the given coloured numbers.

(a) 72 2 4 6 5
(b) 56 4 6 9 14
(c) 318 6 9 3 8

(d) 625 5 3 7 9
(e) 236 6 3 4 2

3. Is 2 a factor of 216?

4. Is 5 a factor of 50?

5. Find the common factors of the following numbers.
(a) 8 and 12 (b) 9 and 15 (c) 12 and 50 (d) 20 and 60

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