How to play

Three steps

Paciolino, a cartoon friar, holding up a quill

Mark every cell
Tap a number to mark it DR (debit), tap again for CR (credit), and once more to clear it.
Balance every line
In each row and each column, the debits must add up to the same total as the credits.
Use logic, not luck
Framed cells are already posted. There is exactly one answer, and you can always reason your way to it.

DRDebitCRCreditThe margins show each line’s DR and CR totals against its target. ✓ means balanced, ✗ means a side is over.

Warm-up · 4×4Easy

Petty Cash

Stuck? Press Hint and Paciolino will explain the next step.

Tap a cell to cycle blank → DR → CR. Keyboard: arrows move, D debit, C credit, Backspace clear, Ctrl+Z undo.

Three techniques

Show tips

Find the half

Add up the line and halve it. That’s what each side needs. A row of 3, 5, 10 and 2 totals 20, so the debits make 10 and the credits make 10.

35102= 20, so 10 a side

The number that stands alone

If one number is exactly half the line, it sits on its own side and everything else goes opposite. Here 10 is half of 20.

35102DR 10 · CR 3+5+2 = 10

A full side closes the line

Once one side reaches its target, every blank cell left in that line belongs on the other side.

6437DR 6+4 = 10, so the rest are CR

Where it began

Paciolino, a cartoon friar, holding a quill and a ledger, with a polyhedron floating beside him

Double Entry

Paciolino’s first ledger

Venice, 1464. A wool merchant’s counting house.

Young Paciolino has been hired to tutor a merchant’s three sons, and on his first morning he finds their father’s books in a terrible state. Coins in, coins out, all scribbled on the same page, and nobody can say where the money went. Paciolino sharpens his quill, rules a line down the middle of every page, and makes a solemn promise: every row will balance, and so will every column. By sunset the merchant knows exactly what he owns, and Paciolino has invented his favourite pastime.

How it works: Mark every amount as a debit or a credit. In every row and every column, the debits must add up to the credits.