Class 7 Maths Fractions and Decimals  Addition and Subtraction of Decimal Numbers 
Addition and Subtraction of Decimal Numbers
Addition of Decimal numbers:
The rules for addition of numbers with Decimals are:
Subtraction of Decimal numbers:
The rules for subtraction are:
Problem: Which is greater? 5 or 0.05
Place Value of digits is compared from the left till we find a greater place value.
Place Value – 0.50 
Relation between place value

Place value 0.05 
0*1 = 0

= 
0*1 = 0 
5*1/10 = 0.5

> 
0*1/10 = 0 
Since 0.5 is greater than 0, there is no need of further comparing the place value of digits. 0.5 is greater than 0.05.
099 or 0.19
Place value is compared:
Place Value – 0.099 
Relation between place value

Place value 0.19 
0*1 = 0

= 
0*1 = 0 
0*1/10 = 0

< 
1*1/10 = 0.1 
Since 0.1 is greater than 0, there is no need of further comparing the place value of digits. 0.19 is greater than 0.099.
Problem: Express as rupees using decimals: 7 paise
1 Rupee = 100 paise
100 paise = 1 Rupee
1 paise =1/100 Rupee
7 paise = 7/100 Rupee
7 paise = 0.07 Rupees
Thus, the answer is 0.07 rupees.
7 rupees 7 paise
1 Rupee = 100 paise
100 paise = 1 Rupee
1 paise =1/100 Rupee
7 paise = 7/100 Rupee
7 paise = 0.07 Rupees
Thus, the answer is 7 rupees + 7 paise = 7 rupees + 0.07 rupees
= 7.07 rupees.
Problem: Write the place value of 2 in the following decimal numbers: 56
2 is located at the one’s place.
Place value of 2 is 2*1 = 2.
(ii) 21.37
2 is located at the one’s place.
Place value of 2 is 2*10 = 20
.