How it is calculated
Each discount multiplies the price by (1 − discount / 100). The second discount is taken from the price that is already lower. “Price before the discount” divides the current price by those same factors.
Discounted price = Price × (1 − s1) × (1 − s2)
Where the numbers come from
- What to find
- Price
- First discount — unit in the field: %
- Second discount — Leave 0 if there is only one discount.
- Quantity — unit in the field: pcs
Example
A price of 1 000 currency units, discounts of 20% and 10%. After the first, 800 currency units are left; after the second, 720. The total cut is 28%, not 30%.
Questions
Why can't I add 20% and 10%?
The second discount is taken off the new price. 10% of 800 currency units is 80 currency units, not 100.
Is a 100% discount allowed?
No. At a price of zero the reverse calculation is undefined.
Why the quantity?
So you can see the total for several identical goods at once. It does not change the price of a single piece.