Practice Set 5.1
1. Write each given number as a product of prime factors :
(i) 69
(ii) 27
(iii) 78
(iv) 126
Solution :
(i) 69 :
3
69
23
23
1
69 = 3 × 23
(ii) 27 :
3
27
3
9
3
3
1
27 = 3 × 3 × 3
(iii) 78 :
2
78
3
39
13
13
1
78 = 2 × 3 × 13
(iv) 126 :
2
126
3
63
3
21
7
7
1
126 = 2 × 3 × 3 × 7
2. Write all divisors of each of the following numbers :
(i) 18
(ii) 56
(iii) 120
(iv) 256
(v) 67
Ans.
(i)
Divisors of 18 : 1, 2, 3, 6, 9, 18
(ii)
Divisors of 56 : 1, 2, 4, 7, 8, 14, 28, 56
(iii)
Divisors of 120 : 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 30, 40, 60, 120
(iv)
Divisors of 256 : 1, 2, 4, 8, 16, 32, 64, 128, 256
(v)
Divisors of 67 : 1, 67