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### Student Question

Secondary I • 2yr.

Hi, I am not sure how to do operations, such as the addition, subtraction, multiplication or division with decimals. Could you explain it to me please?

Mathematics

## Explanations (1)

• Explanation from Alloprof

Explanation from Alloprof

This Explanation was submitted by a member of the Alloprof team.

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Team Alloprof • 2yr.

Hello you !

In a stated operation, we must align the commas of each number one under the other.

When adding decimals, the technique for calculating the addition of decimal numbers is the same as that for whole numbers. We start with the column on the extreme right and add the numbers starting from up to down. When the sum in a place value column is greater than 10, we carry over to the next column to the left. The procedure is the same for the subtraction. It must be taken into account that the comma is placed as to have a decimal part of the same length (or at the same position) in the result number and initial decimal number (e.g. both have 2 numbers after the comma).

Example: 10.2 + 1.2 = 11.4.

Here, just like any other exercise of this kind, we must align the commas. We add the tenths together as well as the units and the decimal part.

To multiply decimals, use the technique for that of natural numbers. On the other hand, you can multiply the numbers by 10, 100, 1000 etc . (power of 10) to remove the decimal portion.

When dividing, you must multiply the numbers by the power of 10 to eliminate the decimal part forming the divisor. Afterwards, we proceed with the method of dividing whole numbers.

I hope I was able to help you! If you still have any difficulty, don't hesitate to rewrite! :)