# Mystery number colour-by-number activity (addition and subtraction within 20)

## This fun activity uses addition and subtraction skills to reveal a mystery number.

Today we have a fun mystery number activity.

It’s a colour-by-number activity but with a bit of a twist. Instead of revealing a picture, the colours will reveal a mystery number instead.

I find colour-by-number activities are always popular. If your child has been working on addition and subtraction skills, this makes a fun review activity to revise lots of facts all in one activity.

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Related: How to add and subtract using a number line

## What math skills does this activity practise?

This worksheet will have your child solving addition and subtraction within 20. (This means that the numbers involved in the addition and subtraction questions will not exceed 20).

Among the questions there is plenty of focus on doubles as well as on number bonds to 10 and 20.

Related post: Balloon number bonds to 10

## How to complete this activity

In order to get started you’ll need to print the sheet and locate some colouring supplies for your child.

Crayons, colouring pencils or markers work well. You’ll need red, yellow, green, blue and purple.

To complete the picture and reveal the mystery number, your child (or students) will have to solve the addition or subtraction questions in each section of the picture.

When they have worked out the answer to a question, they’ll need to check the colour code (above the picture) to see what colour that section should be.

So, for example, this section shows 20 – 2, which gives an answer of 18.

Looking at the code, we can see that any answers of 18, 19 or 20 should be coloured purple.

Gradually, as each section is completed and coloured, the mystery number will be revealed.

Once your child has found out the mystery number, they can write it in the box at the bottom of the page.

And there we have it!

A fun, math-packed mystery number activity, perfect for any child needing to practise addition and subtraction within 20.