Bitcoin & money learning · Retrospective
Do not add monthly percentages mechanically
Use multiplication when a change applies to a new base.
Source foundation
CPI measures changes in consumer prices; it is not an individual household budget. BLS: CPI questions and answers.
A worked example
A hypothetical index grows 1 percent for two consecutive months. Starting at 100, it reaches 101 and then 102.01. The combined gain is 2.01 percent. Adding the two monthly rates gives a close approximation here, but it is not the exact compounded result.
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
Label approximations and distinguish them from exact calculations.
Try it on paper
Compute two consecutive hypothetical declines of 1 percent.
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.