Discounts and increases
A 20% discount means paying 80%: multiply by 0.8. A 20% increase means paying 120%: multiply by 1.2. One factor does the job.
About: Discounts and increases
A 20% discount means paying 80%: multiply by 0.8. A 20% increase means paying 120%: multiply by 1.2. One factor does the job.
Worked examples
A $430 item is 10% off. How much do you pay?
Answer: 387. Multiply by the factor 0.9 (1 − 0.1): 430 × 0.9 = 387.
A $350 bill went up 20%. What is the new amount?
Answer: 420. Multiply by the factor 1.2 (1 + 0.2): 350 × 1.2 = 420.
A $640 item is 15% off. How much do you pay?
Answer: 544. Multiply by the factor 0.85 (1 − 0.15): 640 × 0.85 = 544.