Adding and subtracting positive and negative decimals

Objective: I know how to add and subtract positive and negative decimals or directed numbers.

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!

Try the free Mathway calculator and problem solver below to practice various math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

We hope that the free math worksheets have been helpful. We encourage parents and teachers to select the topics according to the needs of the child. For more difficult questions, the child may be encouraged to work out the problem on a piece of paper before entering the solution. We hope that the kids will also love the fun stuff and puzzles.

We welcome your feedback, comments and questions about this site or page. Please submit your feedback or enquiries via our Feedback page.

Rounding and Decimals:

Addition and subtraction with decimals are just the same as addition and subtraction with the whole number. The most important thing to remember is to line up the decimal points so that when you stack them, they are directly on top of each other. Doing this stacks the place values so that the ones are on top of the ones, the tens on the tens, the tenths on the tenths, and so forth. If there are any times when there aren’t as many digits after the decimal place in one number as there are in another, remember that you can fill in any places to the right of the decimal with a 0. In numbers, this looks like 3.15 = 3.150 = 3.150000000 and so on.

Steps for Addition (Combining Two Positive or Two Negative Numbers)

1. Stack the numbers according to place value. (This will line up the decimals.)
2. Add the numbers in the columns starting with the column on the right.
3. Carry numbers into the next place value to the left as needed.
4. Repeat this pattern for each remaining column.
5. Bring the decimal down.
6. Check sign. (If both numbers were positive, the answer is positive. If both numbers were negative the answer is negative.)

Steps for Subtraction (Combining a Positive and Negative Number)

1. Biggest on top.
2. Stack in columns according to place value. (This will line up the decimals.)
3. Regroup when needed.
4. Subtract in columns by place value starting on the right and going left.
5. Bring the decimal down.
6. Strongest wins. (If the bigger number was negative then the answer is negative. If the bigger number was positive then the answer is positive.)

Video Source (06:14 mins) | Transcript

Video Source (08:49 mins) | Transcript

Additional Resources

• Khan Academy: Adding decimals (02:40 mins)
• Khan Academy: Subtracting decimals (2:08 mins)

Practice Problems

Evaluate the following expression:

1. 2.4 + 8.8 = ?
2. 8.12 + 9.81 = ?
3. 5.92 + 3.22 = ?
4. \(7.2-1.5=?\)
5. \(5.2-5.4=?\)
6. \(39.6-88.88=?\)

Company | Membership | Blog | Help center | User guides | Tell us what you think | Testimonials | Careers | Contact us | Terms of service | Privacy policy

© 2022 IXL Learning. All rights reserved. Follow us

What are the rules for adding positive and negative decimals?

What are the rules for adding and subtracting negative decimals?