7.2.1

Missing Number Problems

Test yourself

Writing Missing Number Problems

To work out missing numbers in problems, you can use algebra!

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Turning sentences into algebra

  • You can turn sentences into algebra.
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Solving algebra

  • To solve something in algebra means to find the number that should go instead of the letter to make the equation work.
    • In this example, n = 13.

Missing Number Problems

You can use missing number problems to find missing numbers in examples in real life.

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Example

  • I am making a cake.
  • The weight of the cupcake case is 12 g.
  • Each cupcake case is filled with different amounts of cake mixture (c).
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The missing number problem

  • The expression to solve this problem is 12 + c = w.
    • 12 is the weight of the cupcake case.
    • c is the weight of the cake mixture.
    • w is the weight of the cupcake.
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Substitution

  • You can work out the missing values in the table by substituting the values into you know into 12 + c = w.
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Weight of mixture = 324 g

  • 12 + c = w
    • 12 + 324 = w
    • w = 336 g
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Weight of cupcake = 356 g

  • 12 + c = w
    • 12 + c = 356
    • c = 356 − 12
    • c = 344 g

Jump to other topics

1Year 5 - Number

2Year 5 - Measurement

3Year 5 - Geometry

4Year 5 - Statistics

5Year 6 - Number

6Year 6 - Ratio & Proportion

7Year 6 - Algebra

8Year 6 - Measurement

9Year 6 - Statistics

9.1Displaying Data

9.2Averages

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