Adding and Subtracting Decimals Calculator That Shows Its Work

Adding and Subtracting Decimals Calculator Sign

This calculator will add or subtract decimals, integers or whole numbers and show its work -- including an explanation for each step taken to arrive at the solution.

You can also enter negative numbers and the calculator will explain how to set up the grid using absolute values, as well as which sign (positive or negative) will apply to the result.

If you need to multiply or divide decimals, please visit either the Long Division Calculator or the Long Multiplication Calculator.

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Adding and Subtracting Decimals Calculator

Add or subtract decimals or integers, including negative numbers, and learn how to solve the addition or subtraction without a calculator.

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Selected Data Record:

A Data Record is a set of calculator entries that are stored in your web browser's Local Storage. If a Data Record is currently selected in the "Data" tab, this line will list the name you gave to that data record. If no data record is selected, or you have no entries stored for this calculator, the line will display "None".

DataData recordData recordSelected data record: None
First number:

First number:

Enter the first number in the addition or subtraction. The number can be a decimal number and can either be positive or negative. To enter a negative number, enter a minus sign in front of the number (-25). To enter a positive number, enter the number without a sign.

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Second number:

Second number:

Enter the second number in the addition or subtraction. The number can be a decimal number and can either be positive or negative. To enter a negative number, enter a minus sign in front of the number (-25). To enter a positive number, enter the number without a sign.

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Result:Result:Calculated result:Calculated result:

Calculated result:

This is the calculated result of adding or subtracting the two numbers. Scroll down to view a suggested method for setting up and solving the addition or subtraction.

If you would like to save the current entries to the secure online database, tap or click on the Data tab, select "New Data Record", give the data record a name, then tap or click the Save button. To save changes to previously saved entries, simply tap the Save button. Please select and "Clear" any data records you no longer need.

Help and Tools

Learn

How to add and subtract decimals and negative numbers without a calculator.

How to Add and Subtract Decimals

To add and subtract decimal numbers without a calculator, both numbers must have the same number of decimal places. This is because the decimal points must line up in the solution grid to add or subtract the decimal numbers.

If it turns out one number has a greater number of decimal places than the other, simply add zeros to the end of the number with fewest decimal places until it has the same number of decimal places as the other.

For example, suppose we are attempting to add the following two decimal numbers:

56.4321 + 12.34

Since the first number has 2 more decimal places than the second number, we need to add 2 zeros to the end of the second number (12.34 becomes 12.3400). That way the decimal points (indicated by a red vertical line) will line up in the solution grid, like this:

← swipe left and right →← swipe left and right →
 564321
+ 123400
=+       

This also ensures that the sum of the two numbers will have the same number of decimal places as the number with the most number of decimal places.

How to Add Negative Numbers

If one or more of the numbers in the addition problem is negative, the steps for adding the numbers depends on whether or not the signs of the two numbers are the same.

If the signs are the same:

Simply add the absolute values of the two numbers and give the sum the same sign as the two numbers.

Example: (-7) + (-2)

Add the absolute value of -7 (|-7| = 7) to the absolute value of -2 (|-2| = 2) to get 9, and give the sum the sign of the two numbers, which in this case is a negative sign.

  
 7
+ 2
=- 9
ColumnAB
If the signs are not the same:

Using their absolute values, subtract the smaller of two numbers from the larger of the two numbers and give the sum the sign of the number with the largest absolute value.

Example: (-7) + (2)

Subtract the absolute value of the smaller number (|2| = 2) from the absolute value of the larger number -7 (|-7| = 7) to get 5, and give the result the sign of the number with the largest absolute value, which in this case is a negative sign.

  
 7
- 2
=- 5
ColumnAB

How to Subtract Negative Numbers

If the problem is subtraction, change the subtraction to addition and change the sign of the last number to its opposite. Then follow the steps for adding negative numbers.

Example #1: (-7) - (2)

Change (-7) - (2) to (-7) + (-2) and follow the rules for addition.

Since the signs are now the same, add the absolute value of -7 (|-7| = 7) to the absolute value of -2 (|-2| = 2) to get 9, and give the sum the sign of the two numbers, which in this case is a negative sign.

  
 7
+ 2
=- 9
ColumnAB
Example #2: (-7) - (-2)

Change (-7) - (-2) to (-7) + (2) and follow the rules for addition.

Since the signs are no longer the same, subtract the absolute value of the smaller number (|2| = 2) from the absolute value of the larger number -7 (|-7| = 7) to get 5, and give the result the sign of the number with the largest absolute value, which in this case is a negative sign.

  
 7
- 2
=- 5
ColumnAB

If you're not sure how to perform long addition or subtraction, the calculator on this page shows its work and includes the solution steps for each calculated result.

Adjust Calculator Width:

Move the slider to left and right to adjust the calculator width. Note that the Help and Tools panel will be hidden when the calculator is too wide to fit both on the screen. Moving the slider to the left will bring the instructions and tools panel back into view.

Also note that some calculators will reformat to accommodate the screen size as you make the calculator wider or narrower. If the calculator is narrow, columns of entry rows will be converted to a vertical entry form, whereas a wider calculator will display columns of entry rows, and the entry fields will be smaller in size ... since they will not need to be "thumb friendly".

Show/Hide Popup Keypads:

Select Show or Hide to show or hide the popup keypad icons located next to numeric entry fields. These are generally only needed for mobile devices that don't have decimal points in their numeric keypads. So if you are on a desktop, you may find the calculator to be more user-friendly and less cluttered without them.

Stick/Unstick Tools:

Select Stick or Unstick to stick or unstick the help and tools panel. Selecting "Stick" will keep the panel in view while scrolling the calculator vertically. If you find that annoying, select "Unstick" to keep the panel in a stationary position.

If the tools panel becomes "Unstuck" on its own, try clicking "Unstick" and then "Stick" to re-stick the panel.