Loading please wait

The smart way to improve grades

Comprehensive & curriculum aligned

Try an activity or get started for free

Deduce the Missing Number in Subtractions Mentally

In this worksheet, students will be asked to use efficient mental methods to subtract mentally. They will use the inverse operation to calculate a missing number.

'Deduce the Missing Number in Subtractions Mentally' worksheet

Key stage:  KS 2

Curriculum topic:   Number: Addition and Subtraction

Curriculum subtopic:   Add/Subtract Mentally

Difficulty level:  

Worksheet Overview

In this activity, you will be asked to find the missing number in a subtraction question.

The key to this activity is calculating every answer mentally (in your head) without using pen and paper.


Example 1

In your head, find the missing number


    - 14 = 24



Use the inverse operation (addition) in order to find the answer

14 + 24 = 38



38 - 14 = 24



Example 2

    - 0.6 = 2



Use the inverse operation in order to find the answer:

2 + 0.6 = 2.6



2.6 - 0.6 = 2



Example 3

34 -  = 11



Use the numbers you have been given to complete a subtraction sum in order to find the missing number

34 - 11 = 23



34 - 23 = 11


This method will make more sense when you attempt to answer some questions.

What is EdPlace?

We're your National Curriculum aligned online education content provider helping each child succeed in English, maths and science from year 1 to GCSE. With an EdPlace account you’ll be able to track and measure progress, helping each child achieve their best. We build confidence and attainment by personalising each child’s learning at a level that suits them.

Get started

Try an activity or get started for free

  • educational
  • bettfutures
  • cxa
  • pta
  • era2016
  • BDA award
  • Explore LearningTuition Partner
  • tacm