The Never-Ending Sum
This is a simple game to pass some time.
It was made by Christian Lawson-Perfect while on strike.
Use the free text area under each sum to do your working-out.
There are no scores or things to unlock - just do as many sums as you like.
Your progress gets saved automatically, so when you've had enough feel free to close the page, and come back to it whenever you feel like doing more sums.
If you've got ideas for sums that could go in the game, please add an issue on GitHub.
It'll probably break if you set the difficulty too high. Think about that.