Original price and two discount percents applied in sequence—final price and equivalent single discount.
Sequentially: price × (1 − first%÷100) × (1 − second%÷100). The “equivalent one‑step off” line is 100 × (1 − final÷original) percent. Each percent must be 0–99.99… (strictly < 100 in checks); second can be left as 0.
This calculator uses plain decimal numbers. If a result looks wrong, check whether you used a comma instead of a dot (or vice versa) where the field expects one.