A change maker (cash register) calculator works out how much change to give a customer and breaks it into the smallest number of notes and coins. It is handy for shop tills, market stalls, teaching arithmetic and double-checking change. Enter the amount owed and the amount paid, and you instantly get the change due plus a denomination breakdown.
How it works
The tool first converts both amounts to whole minor units (cents or pence) to avoid floating-point errors, then subtracts to find the change. It breaks that change down with a greedy algorithm: starting from the largest denomination (100, 50, 20, 10, 5, 2, 1, then 0.50, 0.25, 0.20, 0.10, 0.05, 0.02, 0.01), it takes as many of each as fit, subtracts, and moves down. For standard 1/2/5-style currencies this gives the fewest pieces. If the amount paid is less than owed, it shows the shortfall instead.
Example
A bill of 7.43 paid with 10.00:
change = 10.00 − 7.43 = 2.57
| Denomination | Count |
|---|---|
| 2 | 1 |
| 0.50 | 1 |
| 0.05 | 1 |
| 0.02 | 1 |
That is 2 + 0.50 + 0.05 + 0.02 = 2.57, using just four pieces. Everything runs in your browser with nothing uploaded.