Here's the secret accountants rarely say out loud: profit can be derived from balances alone. Profit is what's left after you remove owner moves from the change in what you own and owe.

If your cash went up $1,200 this month, and you know exactly which big items you spent on, anything unexplained is your small stuff — already bundled, already counted.

That's why NapkinLedger treats the end-of-month balance screen as the anchor. Enter what's really in each cash account. The engine posts the change against principal-cash and your income statement self-corrects.

Receipts tell you how you spent. Balances prove what you ended with. Only one of those is proof.