Bitcoin & money learning · Retrospective
Read change before approving a payment
Separate the recipient amount from money returning to your wallet.
Source foundation
Ordinary Bitcoin transactions spend earlier outputs and create new outputs. Bitcoin developer guide: transactions.
A worked example
In a paper example, a 100,000-satoshi input funds a 25,000-satoshi payment and a 2,000-satoshi fee. The remaining output should be 73,000 satoshis. If a screen instead shows 72,000, there is a 1,000-satoshi difference to explain before approval.
Original hypothetical example. Amounts, people, events, and scenarios above are invented for learning; they are not historical observations or forecasts.
What to take from it
Reconcile every output in the example instead of assuming the largest one is the recipient.
Try it on paper
Write an equation for a payment with two recipients.
Keep the assumptions beside your answer. Check the result before applying the idea to a different situation.
Reading and limits
The linked source supports the foundation statement. The worked example and exercise are NAKAMOTO's educational analysis. This note does not establish current prices, product terms, investment suitability, or wallet compatibility.
Source reviewed 13 September 2026. For operational decisions, consult the current official documentation and the details of your own circumstances.