Algebra and missing number practice
Algebra in primary school starts as missing number problems and grows into simple equations. Noggli practises both, using inverse operations to work backwards.
What your child practises
- Year 2find a missing number in an addition
- Year 3use inverse operations to find missing numbers
- Year 5solve two-step missing-number problems
- Year 6find the value of an unknown in a simple equation (3n + 4 = 19)
- Year 6solve equations involving division and addition
Mix-ups Noggli looks out for
- Picks the wrong way to undo a sum in missing number questions
Missing number problems
For ? + 8 = 20, ask what you add to 8 to make 20, or work backwards: 20 − 8 = 12. Children use inverse operations like this from Year 2 and Year 3.
Year 6 equations
In Year 6 the missing number becomes a letter. For 2n + 9 = 27, take away 9 to get 2n = 18, then divide by 2 to get n = 9. Undoing the steps in reverse order is the key idea.
Helping at home
- Use a box or a cup for the missing number before switching to a letter.
- Check the answer by putting it back in: 2 × 9 + 9 = 27.
- Think of it as a puzzle: what was done to n, and how do we undo it?
Made for children who worry about getting it wrong
A clue, not a cross
A wrong answer gets a clue and another go. A second miss shows how it works, step by step.
No clock
Nothing counts down. Confidence first, speed follows on its own.
The right level
After a few questions Noggli knows where your child is, and every question after that adapts.
Related practice
Questions parents ask
What is algebra in Year 6?
Using letters for unknown numbers, writing simple formulae and solving equations such as 2n + 9 = 27 or 3n − 7 = 2.
How do you solve missing number problems?
Use the inverse operation to work backwards. For ? × 3 + 2 = 32, take away 2 to get 30, then divide by 3 to get 10.
Why does my child add when they should subtract?
Choosing the wrong inverse is a very common slip. Noggli spots it and gives a clue about undoing the last step first.
Practise this every day, at the right level
Noggli works out where your child is in every topic and adjusts each question to suit. Free, with no timers, no scores and no child accounts.