Algebra Basics
A letter is a number in disguise. Start by putting a number in and seeing what comes out, then turn it round and work out which number the letter must have been.
No account, and the maths stays in your browser — more— less
This activity is for learning and practice. Anything it suggests is indicative only — it is not a formal assessment and not a substitute for a teacher or tutor.
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Set your country and age — change
Setting an age keeps the questions at the right level for that age. It does not lock anything — you can still try any topic, at any age, in any order. Levels are a guide only, not a curriculum.
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Saving your progress
Nothing is being saved. You can practise as much as you like — when you close the tab, the session is gone.
You have been doing this for years
2n + 3 = 11 is the same puzzle as 2 × ? + 3 = 11, which is the same puzzle as “I thought of a number, doubled it, added three and got eleven”. Nothing new has happened except that the unknown has been given a name instead of a question mark. If you can do missing numbers, you can do this.
What the writing actually means
- 3n means 3 × n. Not “3 next to n” and definitely not the digits written side by side — if n is 4, then 3n is 12, not 34.
- The letter does not matter. n, x, a, y — they are all just a box waiting for a number. Meeting more than one letter is why this tool does not only ever use n.
Solving: undo the last thing first
To build 2n + 3 you multiply by 2 and then add 3. So to take it apart you go backwards: subtract the 3 first, and divide by 2 second. Doing it the other way round — dividing 11 by 2 before dealing with the 3 — is the most common way these go wrong, and it is why the order matters rather than being a rule to remember.
School levels
School levels are a guide only. They show where a skill is usually taught in each country and are not taken from, aligned to, or endorsed by any curriculum authority. Your school may cover it earlier or later.