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.