Page 72 - Maths Class 04

Next, identify those prime factors that both numbers have in common and
multiply them. Here, both 3 and 5 are common factors. The HCF is 3 times 5

or 15.

HCF = 3 × 5 = 15

Example : Find the HCF of these pairs of numbers.

a. 14, 49 b. 15, 75

Solution : a. 14, 49

List the prime factors of each.

14 = 2 × 7

49 = 7 × 7

7 is common factor. Therefore, 7 is the HCF.

b. 15, 75

List the prime factors of each.

15 = 3 × 5

75 = 3 × 5 × 5

3 and 5 are common factors. Therefore, 3 × 5 = 15 is the HCF.

Practice - 5.2
Practice - 5.2
Practice - 5.2
Practice - 5.2
1. Find the HCF of the following numbers.

a. 30 and 75 b. 24 and 50 c. 28 and 48

d. 36 and 60 e. 8, 12 and 40 f. 144 and 312

g. 135 and 165 h. 225 and 450 i. 405, 426 and 507

j. 531, 726 and 984 k. 225, 340 and 765 l. 165, 205 and 315

2. Make a factor tree for each of the following numbers.

a. 50 b. 63 c. 81 d. 100 e. 136

3. Find the common factors in each of the following.

a. 7, 14 b. 30, 36 c. 21, 15 d. 12, 20

e. 15, 18 f. 16, 28 g. 26, 52 h. 24, 18

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