Percentages and Fractions Summary

Mental Math · Axiom Academy

SUMMARY Percentages and Fractions Master mental math strategies for quick calculations with fractions and percentages in everyday situations. Mental Percentage Calculations 10% Trick: Move decimal point one place left. 5% Trick: Find 10% and halve it. 15% Tip: Find 10% + 5%. Perfect for restaurant tips. 50% Trick: Divide by 2. The easiest percentage calculation. Fraction Simplification Strategies Divide by Common Factors: Look for obvious divisors like 2, 3, 5. Factor Method: Break both numerator and denominator into prime factors. GCD Approach: Find the greatest common divisor and divide both parts. Visual Recognition: Memorize common simplified forms like Quick Mental Conversion Strategies Reversibility: 8% of 50 = 50% of 8 = 4. Switch for easier calculation. Breaking Down: For 17%, calculate 10% + 5% + 2%. Complement Method: For 95%, find 100% - 5% instead. Chain Percentages: Two 10% discounts is NOT 20% off: Adding with Same Denominator: Keep denominator, add numerators: Cross-Multiply for Comparison: To compare and Mixed Number Addition: Add whole parts, then fraction parts separately. Reciprocal for Division: Flip and multiply: Lightning-Fast Mental Math Tips Always look for multiples of 10, 25, or 50 to simplify calculations Round to the nearest easy number, calculate, then adjust Break large percentages into smaller, familiar chunks (10%, 5%, 1%) Convert difficult fractions to percentages for easier comparison Practice with money amounts for practical application

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