Guides
The maths behind
the numbers
What the formulas are, and what they miss. Every example shows its workings.
5 min · 2026-10-12
Why yearly pay does not divide neatly into months
Yearly ÷ 12 and the number in your account are different. Here is every reason why.
Read →6 min · 2026-10-12
How earnings per second are calculated
The formula behind the counter, and why its figures always agree with each other.
Read →5 min · 2026-10-12
Working hours or round the clock: which basis to use
Same salary, a per-second figure six times larger. Here is where the factor comes from.
Read →5 min · 2026-10-12
The trap in simple saving and goal calculations
The formula for monthly saving and time-to-goal, and the four things it quietly assumes.
Read →6 min · 2026-10-12
What to watch for when comparing prices
Why "chicken costs this much" is only ever half true, and how the labels work.
Read →5 min · 2026-10-12
How much does pay have to rise just to stand still?
At 3% a year, what does pay have to be in ten years just to break even?
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