About
Carry the One is a small, free mental arithmetic game for the web. It exists because most maths practice apps are either aimed squarely at young children or buried under accounts, streaks and upsells. This one is a timer, four buttons and an honest score.
What it is for
Arithmetic is one of those skills that decays quietly. Rounding a bill, sanity-checking a number in a meeting, working out whether a discount is worth it — all of it gets slower without practice. A few minutes of drills against a clock is a good way to keep it sharp, and playing against other people is a better way to keep coming back.
How the game is built
Every question is generated fresh rather than pulled from a fixed list, so the same question rarely comes round twice. In a room, all four players’ devices generate the identical sequence from a shared starting value, which is how everyone sees the same question at the same moment.
Scores in a room are worked out on the server rather than on anyone’s phone, because a wrong answer moves other people’s totals too.
A note on the leaderboards
Solo scores are reported by your own browser. Treat the boards as friendly rather than official — they are there to give you something to beat, not to settle arguments.
Who made it
Carry the One is an independent project, built and run by one person. It is free to play and is supported by advertising on the menu and results screens. There are no ads during a game, and there never will be — a timed round with an advert in the middle is not a game worth playing.
Get in touch
Bug reports, ideas and complaints are all welcome. See the contact page.