Tally stick
Notches cut into wood or bone that counted sheep, debts and days long before there were numerals to write down.
The idea is prehistoric — the Ishango bone from the Congo is around 20,000 years old — but its cleverest form is the split tally. A debt was carved as notches across a stick, which was then split lengthwise: the long half went to the creditor, the short stub to the debtor. Since only the original stick's grain matched exactly, it was a tamper-proof receipt that required no literacy.
England's Exchequer kept the national debt on split hazel sticks right up to 1826. When the obsolete tallies were burned in the Palace of Westminster's furnaces in 1834, the fire got out of hand, spread, and razed almost the entire building. Few accounting methods have been retired quite so literally.