Quick Percentage Decreases

Mental Math · Axiom Academy

LESSON Quick Percentage Decreases Master mental math for common discounts: 10% off, 20% off, and 25% off. Calculate sale prices instantly without a calculator. The Strategy: To find 10% off, simply move the decimal point one place to the left, then subtract that amount from the original price. 1. Move decimal left to find 10% of the price 2. Subtract that amount from the original price The Strategy: Find 10% (move decimal left), double it to get 20%, then subtract from the original price. 1. Move decimal left to find 10% 2. Double that number to get 20% 3. Subtract from the original price The Strategy: 25% is exactly one-quarter. Divide the price by 4, then subtract from the original. 1. Divide the original price by 4 (or by 2 twice)

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