One short calculation each day, checked instantly. The numbers change daily and cover the maths used in real robot builds.
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A new puzzle appears each day in your browser. Answers are computed from the numbers, within a small tolerance.
How it is calculated
Each day the page picks one of six problem types using the date as a seed, so everyone sees the same puzzle on the same day. The answer is computed from the numbers shown, using the same formulas as the calculators on this site.
A worked example
Example of a type: a 5 V input with R1 = 10,000 ohm and R2 = 20,000 ohm gives 5 × 20,000 ÷ 30,000 = 3.33 V. Use the calculators to practise: voltage divider, LED resistor, wheel speed, gear train, battery runtime and stepper frequency.
Common mistakes
- Mixing mm and metres in the wheel puzzle.
- Forgetting to convert mA to A.
- Leaving out the efficiency in the gearbox puzzle.
Related
LED and divider calculator, wheel speed, gear train, stepper frequency.
Last reviewed: November 2026. This tool runs in your browser and sends nothing anywhere. Treat its output as a first check, not a guarantee.