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How do I calculate a 20% discount?

Multiply the original price by 0.20 to get the discount amount, then subtract from the original. Or multiply by 0.80 to get the final price directly. Example: $50 × 0.80 = $40.

How do I find the original price from a discounted price?

Divide the sale price by (1 - discount%). Example: sale price $40 with 20% off → $40 ÷ 0.80 = $50 original.

What is a discount percentage?

Discount% = (Savings ÷ Original Price) × 100. If an item is $100 and you save $25, the discount is 25%.