Missing Number

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    Find the Missing Number!

    Tap a level to start - you can always try again!

    Easy

    Nice warm-up

    Medium

    A bit trickier

    Hard

    Go for it!

    About This Game

    Develop early algebraic thinking by finding the missing number in equations. Children learn to work backwards and apply inverse operations, skills that form the foundation for algebra in later years. Problems range from simple gaps to multi-step challenges.

    Top Tip

    Cover the answer and think: what number makes this equation true? Use the opposite operation to check your work.

    Skills You Are Practising
    • Algebraic readiness
    • Inverse operations
    • Equation solving
    • Logical deduction
    • Number relationships
    In the real world

    Patterns on calendars, page numbers, and bus stops use sequences. Spotting the missing piece is early algebra thinking.

    For parents & teachers
    • Ask 'What operation should you use to find the missing number?' — this builds the habit of thinking about inverse operations
    • Frame it as a puzzle: 'Something is hiding in this equation — can you figure out what it must be?'
    • Connect to everyday situations: 'I have some apples and then I get 3 more — now I have 8. How many did I start with?'
    • Move from numbers to letters when ready: 'If ? + 4 = 9, we can also write this as x + 4 = 9 — that is algebra!'

    Who it suits: Missing number problems are suitable from Grade 1 (ages 6-7) through to Grade 6 (ages 10-11). Young children (Grade 1-2) work with simple addition and subtraction gaps. Older children (Grades 4-6) encounter missing values in multiplication and division equations. All levels benefit from this game as a regular algebraic thinking workout.

    Australian Curriculum v9.0

    This game practises these content descriptions. Tap a code to see its full wording and other games for it.

    • AC9M1N02 (Year 1 Mathematics) partition one- and two-digit numbers in different ways using physical and virtual materials, including partitioning two-digit numbers into tens and ones
    • AC9M2N02 (Year 2 Mathematics) partition, rearrange, regroup and rename two- and three-digit numbers using standard and non-standard groupings; recognise the role of a zero digit in place value notation
    • AC9M3A01 (Year 3 Mathematics) recognise and explain the connection between addition and subtraction as inverse operations, apply to partition numbers and find unknown values in number sentences
    • AC9M4A01 (Year 4 Mathematics) find unknown values in numerical equations involving addition and subtraction, using the properties of numbers and operations

    Find games for any curriculum code

    About Missing Number

    Develop early algebraic thinking by finding the missing number in equations. Children learn to work backwards and apply inverse operations, skills that form the foundation for algebra in later years. Problems range from simple gaps to multi-step challenges.

    Skills Practised

    • •Algebraic readiness
    • •Inverse operations
    • •Equation solving
    • •Logical deduction
    • •Number relationships

    How to Play

    Each question shows an equation with a hidden number represented by a question mark. Work out what the missing number must be and select it from the choices.

    Top Tip

    Cover the answer and think: what number makes this equation true? Use the opposite operation to check your work.

    In the real world

    Finding missing numbers is the gateway to algebra. When children solve ? + 4 = 9, they are doing exactly what secondary school students do when they solve x + 4 = 9. Building this habit of 'working backwards' and 'finding the unknown' early makes the transition to formal algebra much smoother and reduces the common secondary school anxiety around algebraic equations.

    Who Should Play This?

    Missing number problems are suitable from Grade 1 (ages 6-7) through to Grade 6 (ages 10-11). Young children (Grade 1-2) work with simple addition and subtraction gaps. Older children (Grades 4-6) encounter missing values in multiplication and division equations. All levels benefit from this game as a regular algebraic thinking workout.

    Tips for Parents and Teachers

    • •Ask 'What operation should you use to find the missing number?' — this builds the habit of thinking about inverse operations
    • •Frame it as a puzzle: 'Something is hiding in this equation — can you figure out what it must be?'
    • •Connect to everyday situations: 'I have some apples and then I get 3 more — now I have 8. How many did I start with?'
    • •Move from numbers to letters when ready: 'If ? + 4 = 9, we can also write this as x + 4 = 9 — that is algebra!'

    Common Difficulties

    Children often try to guess missing numbers rather than using inverse operations to calculate them. Encourage the habit of asking: 'What is the opposite of what the equation is doing?' If the equation adds 5 and equals 11, then the missing number is 11-5=6. Teaching this systematic approach (rather than trial and error) gives children a reliable method that scales to more complex problems.