Money & Payroll
The arithmetic here is trivial; the assumptions are not. The same "0.6% monthly fee" costs nearly twice as much when charged on the original balance instead of the remaining one. The same headline salary differs by tens of thousands once equity and pension contributions are counted.
Each guide states its assumptions before showing the calculation. Anything policy-dependent is dated, because the rules change.
- Equal Principal vs Equal Instalment: The Real DifferenceBoth repayments clear the same loan. One front-loads the pain and saves interest, the other keeps the payment flat. Where the difference comes from, how to compute it, and whether overpaying is worth it.
- Percentage Traps: Why a 50% Loss Needs a 100% GainPercentages are the easiest arithmetic and the easiest thing to misread. Percentage points versus percent, why a 20% rise then a 20% fall is not zero, and why you cannot average growth rates with an average.