How to Play

Last updated September 18, 2026

Carry the One is a mental arithmetic game played against a shrinking clock. Every question gives you four answers and only one is right. There is no typing and no working out on paper — you either see it or you don’t.

The three difficulties

Solo runs

You start with two lives and one level. Every five correct answers in a row moves you up a level, and each level takes a little more time off the clock. A wrong answer or a timeout costs a life. Lose both and the run ends.

Your best score for each difficulty is kept separately, so a good Kiddo run never overwrites a good Expert one.

Playing against other people

A room holds up to four players. Whoever creates it picks the difficulty and how many questions the round runs for — ten, fifteen, twenty or twenty-five — and shares the four-character room code.

Rooms work differently from solo runs. Everyone sees the same question at the same time, and the first answer to reach the server settles it for the whole room:

• Answer correctly first and you take the point.
• Answer wrongly first and you lose a point, while everyone else gains one.
• If nobody answers before the clock runs out, everyone loses a point.

There are no lives in a room. The round runs for its full question count and the highest score wins, which means a bad start is always recoverable — and buzzing in on a guess is genuinely risky.

Keyboard

On a computer, press 1, 2, 3 or 4 to pick an answer instead of clicking.

Installing it

Carry the One can be installed to your home screen from the Install App option on the main menu. It then opens full screen like an ordinary app, and solo runs keep working with no connection. Rooms and leaderboards need to be online.

Reading the clock

The bar across the top is the time left on the current question, and the number beside it counts down in tenths. It turns red in the last third. When it empties, the question is marked wrong — in a solo run that costs a life, and in a room it costs everybody a point.

The clock shortens as you climb. Each level takes a fraction of a second off, so a question at level six is meaningfully tighter than the same question at level one. This is deliberate: the arithmetic stops being the difficulty and retrieval speed becomes it.

Choosing a difficulty honestly

Most people start too high. Kiddo looks trivial written down, but the point is not whether you can do 7 + 8 — it is whether you can do it in under a second, forty times, without a wrong tap. If you are losing lives to hesitation rather than to arithmetic, drop a level.

A reasonable rule: stay on a difficulty until you can finish a run without losing a life, then move up.

Where the time actually goes

Watching people play, almost all lost time falls into three buckets:

• Recalculating. You work out the answer, then check it against the options and start again. Read the options first — often two are obviously wrong and the choice collapses to two.
• Wrong method. Long multiplication in your head will not finish inside five seconds. If you find yourself carrying columns, there is a shortcut you are not using — the techniques page has them.
• Wrong tap. A real answer, entered on the wrong tile. Costs exactly as much as not knowing it.

Estimating instead of solving

Because there are only four options, you frequently do not need the exact answer — you need to know which option is plausible. If the four choices are 306, 314, 286 and 412, and you know the answer is “about 300 and ends in 6”, you are done without finishing the multiplication.

This is the single biggest source of speed in the game, and it is a genuinely useful habit outside it.

Playing in a room

Rooms reward nerve as much as arithmetic. Because a wrong buzz pays a point to everyone else, guessing early is actively expensive — with three other players, one bad buzz is a four-point swing against you.

The counter-intuitive part is that hanging back has a cost too: if nobody answers, everyone loses a point. Sitting out is not free, it is just quietly bad for the whole room.