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E:\Working\Orange_Education\TouchPad_Maths-5\Open file\Maths_5_Chapter-03
\ 19-Nov-2025 Bharat Arora Proof-9 Reader’s Sign _______________________ Date __________

Like common multiples of two or more numbers, common factors of two or more
numbers are found by writing the factors of the numbers and circling or writing down

the common ones among them.
example 2. Find the common factors of 16 and 24.

Solution. Factors of 16 are 1, 2, 4, 8 and 16.

Factors of 24 are 1, 2, 3, 4, 6, 8, 12 and 24.

Common factors are 1, 2, 4 and 8.

example 3. Find the common factors of 15 and 25. Tips
Solution. Factors of 15 are 1, 3, 5 and 15.

Factors of 25 are 1, 5 and 25. Numbers like 16, 18, 24, etc.
which have more than two
Common factors are 1 and 5. factors are called composite

example 4. Find the common factors of 12, 15 and 18. numbers.

Solution. Factors of 12 are 1, 2, 3, 4, 6 and 12.
Factors of 15 are 1, 3, 5 and 15.

Factors of 18 are 1, 2, 3, 6, 9 and 18.

Common factors are 1 and 3.

Exercise 3B

1. Fill in the blanks.
a. A number is a __________ of two numbers if it can divide both without leaving a
remainder.
b. 36 is a __________ of 12 and 4.
c. The common factors of 12 and 18 are 1, 2, 3 and __________.

d. Two numbers can have many common multiples but a limited number of
__________.
e. 5 is a __________ of 20 and 25.

2. State whether the following statements are true (T) or false (F).
a. Every number is a common multiple of itself and 1.

b. 7 is a common factor of 63 and 50.
c. The number 1 is a common factor of any pair of numbers.
d. Common multiples of two numbers are always smaller than both numbers.

e. 12 is a common multiple of 3 and 4.

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Multiples and Factors