Page 189 - New Medley 4 Semester 1

EXERCISE 5.2

A. Find the first five multiples of the following numbers.

1. 5 2. 7 3. 8 4. 9
5. 10 6. 12 7. 15 8. 17

B. Write the following numbers.

1. Multiples of 3 which lie between 15 and 30.

2. Multiples of 8 which lie between 30 and 50.

3. Two multiples of 11 closer to 49.

4. First 3 multiples of 16 greater than 100.

5. Sixth, eighth and tenth multiples of 18.

C. Check whether the second number is a multiple of the first one.

1. 4, 684 2. 5, 164 3. 7, 833 4. 18, 2030

D. Find the smallest common multiples of:

1. 2, 3 2. 5, 6 3. 6, 8 4. 9, 12

5. 10, 15 6. 15, 12 7. 12, 16 8. 16, 20

HCF and LCM

Highest Common Factor (HCF): The greatest number that can divide all

the given numbers is called the highest common factor. Sometimes, it is
also called the Greatest Common Divisor or GCD.

Here, we will find the HCF of the given numbers using the common factor
method.

Example 7: Find the HCF of 24 and 20.

Solution: Factors of 24: 1 , 2 , 3, 4 , 6, 8, 12, 24

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

Here, common factors of 24 and 20 are 1, 2 and 4.

The greatest common factor among 1, 2 and 4 is 4, so, 4 is

the HCF of 24 and 20.

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