RD Sharma 2020 solution class 9 chapter 1 Number System Exercise 1.2

Exercise 1.2

Page-1.13

Question 1:

Express the following rational numbers as decimals:

(i) $\frac{42}{100}$

(ii) $\frac{327}{500}$

(iii) $\frac{15}{4}$

Answer 1:

(i) Given rational number is  

Now we have to express this rational number into decimal form. So we will use long division method as below.

Hence,

(ii) Given rational number is  

Now we have to express this rational number into decimal form. So we will use long division method as below.

Hence,

(iii) Given rational number is  

Now we have to express this rational number into decimal form. So we will use long division method as below.

Hence, $\frac{15}{4}=3.75$

Question 2:

Express the following rational numbers as decimals:
(i) $\frac{2}{3}$

(ii) $-\frac{4}{9}$

(iii) $\frac{-2}{15}$

(iv) $-\frac{22}{13}$

(v) $\frac{437}{999}$

(vi) $\frac{33}{26}$

Answer 2:

(i) Given rational number is  

Now we have to express this rational number into decimal form. So we will use long division method 

Hence,

(ii) Given rational number is  

Now we have to express this rational number into decimal form. So we will use long division method

Hence,

(iii) Given rational number is  

Now we have to express this rational number into decimal form. So we will use long division method

Hence,

(iv) Given rational number is  

Now we have to express this rational number into decimal form. So we will use long division method

Hence,

(v) Given rational number is  

Now we have to express this rational number into decimal form. So we will use long division method

Hence,

(vi) Given rational number is  

Now we have to express this rational number into decimal form. So we will use long division method

Hence,

Question 3:

Look at several examples of rational numbers in the form $\frac{p}{q} (q \ne 0),$ where p and q are integers with no common factors other than 1 and having terminating decimal representations. Can you guess what property q must satisfy?

Answer 3:

Prime factorization is the process of finding which prime numbers you need to multiply together to get a certain number. So prime factorization of denominators (q) must have only the power of 2 or 5 or both.