Page 56 - Math Skill - 4

54 Maths

Example 2: Find the HCF of:
(a) 12 and 16 (b) 24 and 32

Solution: (a) Factors of 12 are 1, 2, 3, 4, 6 and 12.
Factors of 16 are 1, 2, 4, 8 and 16.
Thus, common factors of 12 and 16 are 1, 2, 4

Of these common factors, the highest number is 4.
Thus, HCF of 12 and 16 is 4.

(b) Factors of 24 are 1, 2, 3, 4, 6, 8, 12 and 24.
Factors of 32 are 1, 2, 4, 8, 16 and 32.
Thus, common factors of 24 and 32 are 1, 2, 4 and 8.

Of these common factors, the highest number is 8.
Thus, HCF of 24 and 32 is 8.

Exercise 4.1

1. Fill in the blanks.
(a) 3 × 7 = 21, so 3 and 7 are __________ of 21.

(b) __________ is the smallest factor of every number.
(c) Every number is a factor of __________.

(d) __________ is not a factor of any number.

2. Check whether the first number is a factor of the second number in each of the following
or not.
(a) 5, 60 (b) 9, 72 (c) 8, 36 (d) 12, 136

3. Write all the factors of:
(a) 10 (b) 18 (c) 63 (d) 92 (e) 56

4. Write three factors of the following, other than 1 and the number itself.
(a) 42 (b) 68 (c) 40 (d) 96

5. Write common factors of the following numbers.
(a) 24 and 40 (b) 12 and 18 (c) 24 and 36 (d) 50 and 25

(e) 45 and 30 (f) 18 and 36 (g) 8 and 32 (h) 5 and 10
6. Show that 25 is a factor of 6225.

7. Write the HCF of :
(a) 18 and 36 (b) 9 and 30 (c) 32 and 60

Multiples
Whenever two or more numbers are multiplied together, we obtain a product. This product is
a multiple of each of the numbers being multiplied.