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Subtracting decimals works just like subtracting whole numbers. The one big idea is to keep every digit in its correct place value by lining up the decimal points.
Every place is worth 10 times the place to its right. 1 of any place value always equals 10 of the next smaller place value:
Think about money: to work out $5.00 − $1.27, you have 5 dollars but no dimes or pennies. You trade 1 dollar for 10 dimes, then 1 dime for 10 pennies.
You still have $5.00, but now you can take away 7 pennies, 2 dimes and 1 dollar. The answer is $3.73. Borrowing across zeros is exactly this chain of trades. Try 5 − 1.27 below to watch it happen.
Type any two decimals (or pick an example), then press Next to go through the subtraction one step at a time.
Fill in the answer one digit at a time, starting from the right. Remember the placeholder zeros and borrowing. The cursor moves left for you after each digit.
This free interactive lesson makes subtracting decimals clear and easy to follow. Instead of memorizing rules, learners watch every step on screen, from lining up the decimal points to bringing down the final answer.
Students can type in any two decimals, or choose a ready-made example, and move through the solution one step at a time. Colour highlighting shows exactly which column is being worked on and which column is being borrowed from. When regrouping is needed, the original digit is crossed out and the new value appears above it, just as it would on paper. Placeholder zeros appear in their own colour, so students see why 3.5 and 3.50 are equal.
A simple place-value explanation and a money example show why borrowing works: 1 of any place value always equals 10 of the next smaller place value. Tricky cases, such as borrowing across zeros or getting a negative answer, are explained in plain language.
In the Your Turn section, students solve new problems on their own, get instant feedback on each digit, and can view the full solution whenever they get stuck.
Teachers can project the lesson in class and walk through any problem at their own pace with the Next and Back buttons. The explanations model the exact language students need to describe their thinking. Because the practice section creates a new problem every time, there is an endless supply of exercises for independent work, homework or early finishers.
The Share button creates a link that opens the lesson with a specific problem already loaded, making it easy to send examples to students, parents or colleagues.
The lesson works on computers, tablets and phones, with no sign-up or download needed.
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