RD Sharma Solutions Ex-1.2, Number System, Class 9, Maths Notes | Study RD Sharma Solutions for Class 9 Mathematics - Class 9

Q1. Express the following rational numbers as decimals:

(i) 42/100

(ii) 327/500

(iii) 15/4

Solution:

(i) By long division method

100)  ( 0.42

400

200

Therefore,  42/100 = 0.42

(ii) By long division method

3000

2500

2000

Therefore, 327/500 = 0.654

(iii) By long division method

12

28

20

Therefore, 15/4 = 3.75

Q2. Express the following rational numbers as decimals:

(i) 2/3

(ii) 


(v) 437/999

Solution:

(i) By long division method

18

18

Therefore, 2/3 = 0.66

(ii) By long division method

3600

3600

3600

Therefore, – 0.444

(iii) By long division method

15

45

45

45

Therefore, 2/15 = -1.333

(iv) By long division method

13

78

117

26

39

91

78

117

Therefore,  = – 1.69230769

(v) By long division method

3996

2997

6993

3996

2997

Therefore, 437/999 = 0.43743

Q3. Look at several examples of rational numbers in the form of p/q (q ≠ 0), where p and q are integers with no common factor other than 1 and having terminating decimal representations. Can you guess what property q must satisfy?

Solution: A rational number p/q is a terminating decimal only, when prime factors of q are q and 5 only. Therefore, p/q  is a terminating decimal only, when prime factorization of q must have only powers of 2 or 5 or both.