Shopping
Sale price from the original
Combines the reduction and the subtraction in one multiplication, which is the form to use once the rate is settled.
The Formula
sale = original x (1 - rate)
Combines the reduction and the subtraction in one multiplication, which is the form to use once the rate is settled.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| original | Pre-tax price before any reduction | currency | 120 in the worked example. Tax is not yet included. |
| rate | Discount rate as a decimal | dimensionless | 25 per cent is written as 0.25, so the multiplier becomes 0.75. |
| sale | Price after the discount, before tax | currency | 120 x 0.75 = 90.0 in the worked example. |
What Each Symbol Means
originalcurrency
Pre-tax price before any reduction
120 in the worked example. Tax is not yet included.
ratedimensionless
Discount rate as a decimal
25 per cent is written as 0.25, so the multiplier becomes 0.75.
salecurrency
Price after the discount, before tax
120 x 0.75 = 90.0 in the worked example.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate a discount page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate A Discount, filed under Everyday Life. Every number the guide produces comes from substituting into this one line.