How to Multiply Decimals, Step by Step

To multiply decimals, you don't need to line anything up. Multiply as if there were no decimal points, then put the point back in the right place by counting decimal places.

Try it with your own problem ↓

The steps

Ignore the decimal points and multiply the numbers as whole numbers.
Count the digits after the decimal point in the first number.
Count the digits after the decimal point in the second number and add the two counts.
In the answer, start at the right and move the decimal point left by that many places.

A worked example

Work out 2.4 × 1.3.

Ignore the points: 24 × 13. Compute 24 × 3 = 72 and 24 × 10 = 240, then 72 + 240 = 312.
2.4 has 1 decimal place and 1.3 has 1 decimal place, so the answer has 1 + 1 = 2 decimal places.
Move the point two places from the right in 312: 3.12.

2.4 × 1.3 = 3.12. Estimate: 2.4 is about 2.5 and 1.3 is about 1.2, and 2.5 × 1.2 = 3, so 3.12 is reasonable.

Try it with your own problem

Open the free The Product Ladder with this example already filled in. It shows every step, and you can type over it with your own numbers.

Work it out: 2.4 * 1.3Opens The Product Ladder with this example

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Common mistakes

Lining up the decimal points like addition. Not needed for multiplying.
Counting the wrong places. Add the number of decimal places in both factors, not just one.
Miscounting places when the product ends in zero. For 0.6 × 0.25: 6 × 25 = 150 and there are 3 decimal places, so the answer is 0.150 = 0.15.
Forgetting that the answer can be smaller. Multiplying by a number less than 1 makes the product smaller.

Questions people ask

Why does counting decimal places work?

Each decimal place divides by 10. Taking the points out multiplied each number by a power of 10, so you divide the product by those same powers.

How many decimal places should my answer have?

The sum of the decimal places of the two numbers you multiplied. You can drop zeros at the end.

How do I multiply a decimal by 10 or 100?

Move the decimal point one place right for 10, two places for 100.

Keep learning

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