How to Do Decimals, Step by Step (With Examples)

Q: How do you add and subtract decimals?

Line up the decimal points so each place value sits in the same column, add zeros so both numbers have the same number of decimal places, then add or subtract as with whole numbers and bring the point straight down.

Q: How do you multiply decimals?

Ignore the decimal points and multiply the digits as whole numbers. Then count the total number of decimal places in both factors and place the point that many digits from the right of the answer.

A MathHelp247 guide · Decimals · Grades 4–6

A decimal point separates the whole-number part of a number from the part that is less than one. Working with decimals uses the same skills as whole numbers — you just have to keep track of the point. Here's each operation with a worked example.

Want your own decimals worked out with steps? Open the Decimal Calculator →

Adding and subtracting decimals

The golden rule is to line up the decimal points. Add zeros so both numbers have the same number of decimal places, then add or subtract as usual and bring the point straight down.

Add 2.75 + 3.4.
Give both two decimal places: 2.75 and 3.40.
Add as whole numbers, keeping the point lined up: 275 + 340 = 615.

2.75 + 3.4 = 6.15

Multiplying decimals

Ignore the points, multiply the digits, then count decimal places and put the point back.

Multiply 0.2 × 0.3.
Ignore the points and multiply: 2 × 3 = 6.
Count decimal places: 1 + 1 = 2.
Put the point 2 places from the right: 0.06.

0.2 × 0.3 = 0.06

Dividing decimals

Make the divisor (the number you're dividing by) a whole number by moving its decimal point to the right. Move the point in the other number the same number of places, then divide.

Divide 2.5 ÷ 0.5.
Move both points one place right: 2.5 ÷ 0.5 becomes 25 ÷ 5.
Divide: 25 ÷ 5 = 5.

2.5 ÷ 0.5 = 5

Converting a decimal to a fraction

Write the digits after the point over the matching place value (10, 100, 1000…), then simplify.

Convert 0.75.
There are two digits after the point, so write it over 100: 75/100.
Simplify by dividing both by 25: 3/4.

Converting a decimal to a percent

Multiply by 100 (move the point two places right). So 0.75 = 75% and 0.4 = 40%. This connects directly to percentages and fractions — they're three ways of writing the same value.

Frequently asked questions

How do you add and subtract decimals?

Line up the decimal points, give both numbers the same number of decimal places, then add or subtract and bring the point straight down.

How do you multiply decimals?

Multiply the digits ignoring the points, then count the decimal places in both numbers and place the point that many digits from the right.

Where can I practice with steps shown?

Use the free Decimal Calculator to add, subtract, multiply, divide or convert decimals with the working shown.