Reduce a number by a percentage. Useful for discounts, falling value, price cuts, and anything that shrinks by a set percentage.
The percentage is applied to the original value to find the amount of the decrease.
That amount is subtracted from the original value.
A decrease of 100% reduces the number to zero; anything beyond that goes negative.
Decrease amount: Value × Percent ÷ 100
Result: Value − Decrease
An item priced at ₹200 is reduced by 15%.
Original price: ₹200
Decrease: 15%
Find the decrease: 200 × 15 ÷ 100 = 30
Subtract it: 200 − 30 = 170
Answer: ₹170 (a reduction of ₹30)
Why doesn't a 50% rise followed by a 50% fall return to the start?
Each percentage is worked out on a different starting number. 100 rising by 50% gives 150. But 150 falling by 50% gives 75, not 100 — because the fall is worked out on the bigger number.
How do I find the original price before a discount?
Divide by (1 − percent/100). An item now priced at ₹170, after a 15% discount, was originally 170 ÷ 0.85 = ₹200.