Question 1

How do I calculate the price after a discount?

Accepted Answer

Multiply the original price by (1 − discount/100). For 30% off $80: $80 × (1 − 0.30) = $80 × 0.70 = $56. Or: calculate savings first ($80 × 0.30 = $24), then subtract ($80 − $24 = $56). Both methods give the same answer. The multiplier method (× 0.70) is faster in your head.

Question 2

How do I find what percentage discount was applied?

Accepted Answer

Discount% = ((Original − Final) / Original) × 100. Example: item was $150, now $105. Savings = $45. Discount% = (45/150) × 100 = 30%. The item is 30% off.

Question 3

How do I calculate two sequential discounts?

Accepted Answer

Multiply the discount factors (do NOT add the percentages). 20% off then 10% off: multiply (0.80 × 0.90) = 0.72 = 28% total discount (not 30%). Example: $100 → $80 (after 20%) → $72 (after 10%). Total saved: $28 = 28% off original. Sequential discounts are always less than their sum because the second applies to the already-reduced price.

Question 4

What is the original price if I know the final price and discount?

Accepted Answer

Original Price = Final Price / (1 − Discount%/100). Example: you paid $84 after a 30% discount. Original = 84 / 0.70 = $120. Common mistake: adding 30% to $84 gives $109.20 — that's wrong because 30% of $84 ≠ 30% of $120.

Question 5

How do discount stacking work for "buy two get one free" offers?

Accepted Answer

"Buy 2 get 1 free" effectively gives 33.3% discount (1 free item out of 3). "Buy 3 get 1 free" = 25% discount (1 free out of 4). "Buy 1 get 1 half price" = 25% effective discount (half price on one = 50% off that item / 2 items total). Always express bundle deals as equivalent percentage off to compare with regular % discounts.

Question 6

Does applying a discount before or after tax change the final price?

Accepted Answer

Yes. Discount before tax: discounted price is the tax base. Final = (Original × (1 − discount)) × (1 + tax). Discount after tax: tax applied first, then discount on the total. Final = Original × (1 + tax) × (1 − discount). Both give the same mathematical result! (1−d)(1+t) = (1+t)(1−d). The only scenario where order matters is when the discount is applied to a subset of items and tax has exemptions.

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