Untangle the Usual Questions
These are the questions beginners ask most often. None of them are silly; every experienced solver once asked them too.
Getting started
Which puzzle should I try first?
An easy Sudoku or a small 10×10 nonogram. Both have short rules, need no arithmetic and let you practise justifying each step. The challenge families list shows other gentle entry points.
Do I need to be good at maths?
No. Sudoku uses digits only as labels, and nonograms, logic grids and tangrams involve no calculation. KenKen and Kakuro use simple addition and multiplication, which you can do on paper.
Should I use pen or pencil?
Pencil, at least at first. Pencil marks for candidates are a normal part of solving, not a sign of weakness. Many apps offer a notes mode that does the same job.
When you are stuck
Is guessing allowed?
Nothing forbids it, but a well-constructed puzzle never requires a guess. If you feel forced to guess, try a case split instead: follow each option a few steps and see whether both lead to the same conclusion. That is reasoning, not guessing.
Why do I always stall halfway through?
The middle of a puzzle is where easy steps run out and you need a second technique. Scan systematically: every digit in every box, then every row, then every column. If that finds nothing, look up one new technique, such as naked pairs, on our Number Play page.
I made a mistake and can't find it. What now?
It happens to everyone. If you can, restart and justify every mark out loud. If not, erase back to the last step you are certain of. Then note the slip in a mistake notebook; it is the most useful thing a wrong answer can give you.
Bigger questions
Will puzzles prevent memory loss or dementia?
There is no reliable evidence that puzzles or brain games prevent or treat dementia or other cognitive conditions. Practice clearly improves performance on the puzzles you practise. If you have a health concern, please speak with a doctor. See our honest limits section for sources.
Is solving faster the same as getting better?
Not quite. Speed tends to follow understanding, but racing can encourage guesses. We suggest measuring progress by the hardest step you can explain, not the time on a clock.
Who invented Sudoku?
The modern form appeared in 1979 as "Number Place" in a Dell puzzle magazine, usually credited to Howard Garns. Nikoli named it Sudoku in Japan in 1984, and The Times brought it to a mass audience in 2004.
Are there good free puzzles online?
Yes. Simon Tatham's Portable Puzzle Collection is free and open source, with dozens of logic puzzle types and no advertising.