# Use Inverse Operation to Find Mystery Numbers in Decimal Calculations

In this worksheet, students will practise their decimal addition facts by using subtraction to find the missing number.

Key stage:  KS 2

Curriculum topic:   Number: Fractions, Decimals and Percentages

Curriculum subtopic:   Solve Problems with Decimal Places

Popular topics:   Decimals worksheets

Difficulty level:

#### Worksheet Overview

Can you work out the missing number in the decimal addition problem?

____ +  3.87 = 5.99

To work this out, we must subtract:

5.99 - 3.87 = ?

We use the inverse to help to find the missing number.

When adding and subtracting decimals, we need to be very careful setting the calculation out so that the decimal points are lined up exactly.

5.99

3.87

5.99 - 3.87 = 2.12

So, to go back to our original problem:

2.12 + 3.87 = 5.99

Let's have a go at some questions on this now.

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