Slow Squares

Printable Binary Blocks puzzles

Binary Blocks is a board of zeros and ones. Fill in the missing digits so that every row and every column holds as many zeros as ones and nowhere three alike stand side by side. On the board lie blocks drawn with an outline — every cell of a block holds the same digit. Few digits are given; the blocks tell the rest.

Every day there is a new board in each of three sizes, dealt to everybody alike and solvable without a single guess. Pick a size, print the sheet, and take it wherever a screen would not go — a pen is all it takes.

Today’s sheets

A4, black and white, one puzzle a sheet, with how to play on the last page. No sign-up, nothing to fill in.

A new set every day at midnight UTC.

How to play

Put a filled or a hollow square in every empty cell so that each row and each column holds as many of one as of the other.

Never three alike side by side — not in a row, not in a column.

Every cell of a block holds the same square.

Tap a cell for a filled square, tap again for a hollow one, once more to clear it. The squares the board came with stay put: tap one and they all give a shake, to show which they are.

Shown in red: three of the same kind side by side, squares a row or column has too many of, and a block holding both kinds.

Solved: three filled and three hollow squares in every row and every column, nowhere three alike together, and one kind of square in every block.

Solving techniques

Questions people ask

Is it free?
Yes. The sheets, the boards on the site and the archive are free, without an account and without advertising. The PDFs are made once a day and anyone may download them.
How many puzzles are there a day?
One new board a day at each level — 8 × 8, 10 × 10, and 12 × 12 — the same for everybody, dealt at midnight UTC. Earlier days stay downloadable in the archive below.
Do I need to sign up?
No. Every sheet downloads without an account. An account only keeps your online plays and your streak in one place across your devices.
Does every puzzle have exactly one solution?
Yes. Every board is checked to have a single solution and to be solvable by reasoning alone — no guessing is ever needed. The solution is not printed; the sheet holds the puzzle and the rules.
May I hand the sheets out or use them in a classroom?
Yes — print, photocopy and hand them out as you like, for a class, a club or a waiting room. Only leave the credit line at the foot of the sheet where it is.

Earlier days

The first sheets are on their way — the archive fills in as the days go by.

No timer. Leave and come back — it’s saved.

Play today’s Binary Blocks online