Decimal calculator with steps
Add, subtract, multiply and divide decimals, with every step shown: lining up the points, column working and moving the point.
🧒 Kids: type two numbers, tap +, −, × or ÷, and read the steps. Then try it on paper!
Decimal calculator
What the calculator shows
Every answer comes with the steps a teacher would want to see. Adding and subtracting show the numbers in columns with the points lined up and zeros filled in. Multiplying shows the whole-number product and the count of decimal places. Dividing shows how to move the points so the divisor is a whole number.
Use it to check homework, not to replace it. Ask your child to solve the problem first, then compare their working line by line. Most decimal mistakes are a point in the wrong place, and the steps show exactly where it went wrong.
Ready-made examples to try
Each link opens the calculator with the problem filled in.
- 3.5 + 1.25: Add with different numbers of decimal places
- 12 − 4.75: Subtract from a whole number
- 6.4 − 0.38: Subtract with regrouping across the point
- 2.3 × 0.4: Multiply two decimals
- 4.25 × 6: Multiply a decimal by a whole number
- 7.2 ÷ 3: Divide a decimal by a whole number
- 3.25 ÷ 2.5: Divide by a decimal
- 1 ÷ 3: A division that never ends
How to add and subtract decimals
- Line up the decimal points, one under the other.
- Fill empty places with zeros so both numbers have the same number of decimal places: 3.5 becomes 3.50.
- Add or subtract column by column from the right, carrying or regrouping as with whole numbers.
- Bring the point straight down into the answer.
A whole number has a point at the end: 12 = 12.00. So 12 − 4.75 = 12.00 − 4.75 = 7.25. See adding decimals for pictures.
How to multiply decimals
Multiply as if there were no points, then put the point back. Count the digits after the point in both numbers; the answer has that many. For example, 2.3 × 0.4: 23 × 4 = 92, and 1 + 1 = 2 places, so 0.92.
Estimate first to catch a misplaced point: 2.3 × 0.4 is about 2 × 0.5 = 1, so 0.92 makes sense and 9.2 does not. See multiplying decimals.
How to divide decimals
Dividing by a whole number is like normal division: keep the point straight above in the answer. 7.2 ÷ 3 = 2.4.
To divide by a decimal, make the divisor a whole number first. Move the point in both numbers the same number of places to the right: 3.25 ÷ 2.5 becomes 32.5 ÷ 25. The answer doesn’t change, because both numbers were multiplied by 10. Then 32.5 ÷ 25 = 1.3.
Divisions that never end
Some divisions keep going: 1 ÷ 3 = 0.333… and 2 ÷ 7 = 0.285714…. The calculator rounds these to 3 decimal places and uses the ≈ sign, meaning “about”. In grade 7 children learn to write repeating decimals with a bar over the digits that repeat.
Common decimal mistakes the steps catch
- Lining up the last digits instead of the points when adding. The column working shows the points lined up.
- Counting the decimal places wrong when multiplying. The steps count them for both numbers.
- Moving only one point when dividing by a decimal. The steps move both.
- Forgetting zeros: 6.4 − 0.38 needs 6.40 first. The column working fills them in.
Decimal operations by grade
| Grade | What children calculate | Standard |
|---|---|---|
| Grade 4 | Add tenths and hundredths as fractions; money | 4.NF.C.5, 4.MD.A.2 |
| Grade 5 | Add, subtract, multiply and divide decimals to hundredths | 5.NBT.B.7 |
| Grade 6 | All four operations with multi-digit decimals, fluently | 6.NS.B.3 |
In India, adding and subtracting decimals comes in class 5 and 6, and multiplying and dividing decimals in class 7.
For teachers
Project the calculator and ask the class to predict each step before it appears. To set homework checks, share a link with the problem filled in: add ?a=4.25&b=6&op=mul to the address (op can be add, sub, mul or div). Nothing is stored and no login is needed.
More decimal help
- Decimals quiz for grades 4 to 6, and decimal levels to learn step by step, and decimal games.
- Decimal practice: 10 questions on any skill, marked as you go.
- Interactive decimal place value chart.
- Worksheets: adding and subtracting decimals · multiplying decimals · make a decimals test
Back to decimals for kids.
Last reviewed
Questions parents ask
How do I use the decimal calculator?
Type the first number, choose +, −, × or ÷, and type the second number. The answer appears straight away with every step, and adding and subtracting show the column working.
How do you add decimals?
Line up the decimal points and add zeros so both numbers have the same number of decimal places. Then add column by column as with whole numbers. For example, 3.5 + 1.25 = 3.50 + 1.25 = 4.75.
How do you multiply decimals?
Ignore the points and multiply as whole numbers. Then count the decimal places in both numbers and put that many in the answer. For example, 2.3 × 0.4: 23 × 4 = 92, two places, so 0.92.
How do you divide by a decimal?
Move the point in both numbers the same number of places to the right, until the divisor is a whole number. Then divide. For example, 3.25 ÷ 2.5 = 32.5 ÷ 25 = 1.3.
What if a division never ends?
Some divisions, like 1 ÷ 3, give digits that go on for ever. The calculator rounds these to 3 decimal places and shows the ≈ sign.
Is it OK for my child to use a decimal calculator?
Yes, for checking. Ask your child to work the problem on paper first, then compare each step. Most mistakes are a point in the wrong place, which the steps show clearly.