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Missing number problems

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Explainer Video

Tutor: Alice

Summary

Missing number problems

In a nutshell

Expressions involving an unknown number are needed to solve missing number problems. Unknown numbers are usually represented by letters.

Example 1

$x + 10 = 12$

This is the same as asking: "what is added to $10$ to get $12$ ?"

The answer is $x=2$

Note: $x$ is the letter commonly used for an unknown.

Method for solving

Procedure

1.	Write out an equation
2.	Work out the value of the unknown

Example 2

Anna has $£20$ . She shares $£5$ with her brother and uses $£12$ to buy a new dress. how much money does she have left?

Write an expression:

$5 + 12 + x = 20$

Solve for $x$ :

 $x= 3$ 

Anna has $\underline{£3}$ remaining.

Learn with Basics

Length:

Unit 1

Two-step problems with addition and subtraction

Unit 2

Adding and subtracting money

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Optional

Unit 3