The Daily Calcudoku

Today’s square, at any side from 4×4 to 9×9. It is cut from today’s date, which is why yours and everybody else’s are the same board.

Puzzle #1 Medium Time 0:00 Filled 0/36

single cell, 5	cage adding to 13	single cell, 3	cage with a quotient of 3	cage adding to 10	single cell, 1
cage adding to 6					cage adding to 13
		cage adding to 10	cage adding to 13
single cell, 2
cage adding to 14		cage adding to 7		cage adding to 7
	cage with a difference of 3				single cell, 5

Show mistakesShow the clockPencil marks

A medium 6×6 square with 16 cages. Click a cell and type a digit; hold shift to pencil one in.

Check this before you rely on it. This calcudoku puzzle generator is provided free and without warranty, and its results are not professional advice.

Your record

—Current streak
—Longest streak
—Days played
—Best time, this size

No server, and no need for one

No server holds a puzzle of the day here and hands it out on request; the calendar does that job instead. The date becomes a number, the number drives every choice the cage carver makes, and the same number therefore cuts the same cages out of the same square on any machine running this code, with no coordination and no request.

Cages make that arrangement work harder than the other two puzzles on this site do. A square is laid down, every cell starts as a cage of its own, and pairs of cages are then merged one at a time — each merge kept only if the solver can still finish what is left. Your browser therefore does not fetch today’s board so much as re-derive it, running through a few hundred small decisions in the time it takes the page to settle.

Because the whole thing is a function of the date, every board is reconstructible forever. A link to a Thursday in March opens the exact square people were filling in that Thursday, five years from now, on a computer that has never contacted this site.

The week is an arch

Difficulty follows the weekday, read in UTC so everyone turns the page at the same moment. Sunday and Saturday are the gentle ends, Wednesday is the peak, and the two days on either side of it climb and descend. There is no day of the week that is always the same difficulty as the day before.

That shape was chosen against the other two sections rather than in isolation. The binary week puts its wall on Sunday and the bridges week saves one for Saturday; putting the peak here in the middle means somebody working through all three puzzles meets a stiff board and a kind one on every single morning, instead of three walls on one and three warm-ups on another.

Side is an independent choice and does not touch the difficulty at all. A gentle 9×9 is a long sit rather than a hard one — the same few observations, made forty more times. Pick the side for the time you have and the day for how much you want to be made to think.

What the streak counts, and what a hint costs

Finishing any one side records the day. Playing all six does not record six, there is no table to climb, and the number is only a record of having turned up — which is the one honest thing a daily puzzle can measure about anybody.

A hint names the argument it used and links to the page explaining it, so taking one is the site doing its job rather than a defeat. It does not break a streak. It is also not quietly left out of the shareable result: the text you copy says how many you took, because a time set with five hints and a time set with none are different results and pretending otherwise would make the whole thing pointless.

The clock can be turned off entirely if being timed spoils the puzzle for you, and the setting sticks. Streak, history and best time per side all live in this browser’s local storage, are never transmitted anywhere, and vanish for good if you clear site data for this domain.

Common questions

Does everybody get the same calcudoku each day?

Yes. The square is cut from the date rather than delivered from anywhere, and every step of the carve is deterministic, so one date and one side produce an identical board in every browser on earth.

Does taking a hint spoil my streak?

Not at all. The hint names the argument it applied and links to the page that teaches it, which is what this site is for. Only whether you finished the board counts towards the streak.

Why is there a short pause before a large board appears?

Because it is being cut. Cages are merged one pair at a time and each merge is tested against the solver, so a 9×9 involves several hundred small checks before the board is fit to publish.