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Adding and Subtracting Decimals – Explanation & Examples

Addition and subtraction of decimals seem to be a bit complex as compared to performing the operations on whole numbers. In this article, we are going to learn how to perform the addition and subtraction of decimals with ease.

And for this case, after reading this article, you won’t spend sleepless nights worrying about how to add and subtract decimals, because the explanations have been step by step simplified for you to understand.

How to Add Decimals?

Addition of decimal numbers is done using the following steps:

  • First, the decimals numbers are written one number under each other so that decimal points are lined up.
  • The numbers are converted to like decimals by attaching the zeros. The number of zeros attached depends on the number with the maximum digits after the decimal point.
  • The digits of each numbers are lined up so that each column contains digits in the same place.
  • Addition is carried out the normal way by starting from the right to the left.
  • The decimal point is then placed in the place as the numbers above it.

Example 1

Add the following decimals: 0.9, 236.8, 1.83 and 21.105.

Solution

We can solve this problem easily by following the steps outlined above:

  • Convert the numbers to like decimals and arrange them one above each other.
  • Perform the normal addition starting from the right.
     
     0.900   
 236.800   
     +                 1.830   
   21.105   
   260.635   

The sum is 260. 635

Example 2

Add the following numbers: 7.39, 65.007, 213.8 and 91.2.

Solution

  • Convert the numbers to like decimals and arrange them one above each other.
  • Perform the normal addition starting from the right.
    
     7.390  
   65.007  
          +213.800  
   91.200  
 377.397  

The answer is 377. 397.

How to Subtract Decimals?

To perform subtraction operation on decimals numbers, the following steps are followed:

  • Write down the decimal numbers, in a column so that the decimal points are lined up.
  • Convert the given decimals to like decimals by attaching zeros.
  • Write the larger number above the smaller number in a column.
  • Arrange the numbers to be subtracted a column so that the all the digits are in the same place.
  • Perform the usual subtraction starting from the right.
  • Place the decimal point in the answer in the same position as the numbers above it.

Example 3

Subtract: 27.59 from 31.4.

Solution

  • Convert the two decimal numbers into like decimals by attaching a number of zeros.
  • Arrange the numbers in a column with the smaller number being at the bottom
    
 31.40  
  –        27.59  
                 3.81  

The answer is 3.81.

Example 4

Subtract: 402.1 – 243.86.

Solution

  • Convert the numbers to like decimal numbers.
  • Arrange the numbers in a column.
    
  402.100  
  –         243.86  
                158.24  

The answer for subtraction is 158.24.

Practice Questions

  1. A man bought a shirt at $ 33 and 65 cents, a coat for $21 and a belt for $9 and 7 cents. Find the total money spent by the man on buying a shirt, coat and belt?
  2. The weight of three metals is 85. 99 kg, 107.81 kg and 19.207 kg. Calculate their total weight.
  3. A student had $100 pocket money. If she bought a book for $ 61.35 and kept the rest. How much money did she keep?
  4. Find the difference between two numbers if the larger number is 107.06 and the smaller number is 79.17
  5. A doctor prescribes a dose for a patient. If a patient is required to take 1.12 liters of a fluid in 24 hours. How many liters of the fluid is left in a bottle containing 2.1 liters of fluid if the patient is given the prescribed amount of the dose
  6. A man had $ 368.29 in his savings account. He withdrew all the money and gave $ 253.46 to his wife and $ 57.39 to his son. How much money is he left with?
  7. Mike had $ 38 pocket money. He spent $ 99.37 for bus fare and donated $ 124.93 to a charity club. How much money is left with him?
  8. Three cows have a total weight of 28 kgs. If two of the cows are 238.94 kgs and 110.09 kgs. Find weight of the third cow?

 

Answers

  1. $63.72.
  2. 007 kgs.
  3. $38.65
  4. 89
  5. 98 liters
  6. $ 679.14
  7. $ 245.08

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