Q-1: Write all the factors of the following numbers:
(a) 24
(b) 15
(c) 21
(d) 27
(e) 12
(f) 20
(g) 18
(h) 23
(i) 36
Solution:
(a) 24
24 = 1 × 24
24 = 2 × 12
24 = 3 × 8
24 = 4 × 6
Hence, the factors of 24 are 1, 2, 3, 4, 6, 8, 12 and 24
(b) 15
15 = 1 × 15
15 = 3 × 5
Hence, the factors of 15 are 1, 3, 5 and 15
(c) 21
21 = 1 × 21
21 = 3 × 7
Hence, the factors of 21 are 1, 3, 7 and 21
(d) 27
27 = 1 × 27
27 = 3 × 9
Hence, the factors of 27 are 1, 3, 9 and 27
(e) 12
12 = 1 × 12
12 = 2 × 6
12 = 3 × 4
Hence, the factors of 12 are 1, 2, 3, 4, 6 and 12
(f) 20
20 = 1 × 20
20 = 2 × 10
20 = 4 × 5
Hence, the factors of 20 are 1, 2, 4, 5, 10 and 20
(g) 18
18 = 1 × 18
18 = 2 × 9
18 = 3 × 6
Hence, the factors of 18 are 1, 2, 3, 6, 9 and 18
(h) 23
23 = 1 × 23
Hence, the factors of 23 are 1 and 23
(i) 36
36 = 1 × 36
36 = 2 × 18
36 = 3 × 12
36 = 4 × 9
36 = 6 × 6
Hence, the factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18 and 36
Q-2: Write the first five multiples of:
(a) 5
(b) 8
(c) 9
Solution:
(a) The required multiples of 5 are:
5 × 1 = 5
5 × 2 = 10
5 × 3 = 15
5 × 4 = 20
5 × 5 = 25
Hence, the first five multiples of 5 are 5, 10, 15, 20 and 25
(b) The required multiples of 8 are:
8 × 1 = 8
8 × 2 = 16
8 × 3 = 24
8 × 4 = 32
8 × 5 = 40
Hence, the first five multiples of 8 are 8, 16, 24, 32 and 40
(c) The required multiples of 9 are:
9 × 1 = 9
9 × 2 = 18
9 × 3 = 27
9 × 4 = 36
9 × 5 = 45
Hence, the first five multiples of 9 are 9, 18, 27, 36 and 45
Q-3: Match the items in column 1 with the items in column 2.
Column 1 Column 2 (i) 35 (a) Multiple of 8 (ii) 15 (b) Multiple of 7 (iii) 16 (c) Multiple of 70 (iv) 20 (d) Factor of 30 (v) 25 (e) Factor of 50 (f) Factor of 20
Solution:
| Column 1 | Column 2 |
| (i) 35 | (b) Multiple of 7 |
| (ii) 15 | (d) Factor of 30 |
| (iii) 16 | (a) Multiple of 8 |
| (iv) 20 | (f) Factor of 20 |
| (v) 25 | (e) Factor of 50 |
Q-4: Find all the multiples of 9 up to 100.
Solution:
9 × 1 = 9
9 × 2 = 18
9 × 3 = 27
9 × 4 = 36
9 × 5 = 45
9 × 6 = 54
9 × 7 = 63
9 × 8 = 72
9 × 9 = 81
9 × 10 = 90
9 × 11 = 99
∴ All the multiples of 9 up to 100 are 9, 18, 27, 36, 45, 54, 63, 72, 81, 90 and 99.
