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Percentage Increase and Decrease

Learn how to calculate percentage increase and decrease using the formula: original value × (1 ± percentage change). Let's get started! 🚀

Percentage Increase and Decrease - introduction visual

Video Lesson

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Flashcards

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Formula for percentage increase and decrease with examples showing 100 increasing by 20% and decreasing by 10%.Percentage increase and decrease examples showing a score increase from 60 to 72 and a jacket price reduced from $90 to $63.Reverse percentage example showing how a $36 ticket with 40% discount gives an original price of $60.

🛎️ The Percentage Formula

  • New value = original value × (1 ± percentage change)
  • Use “+” for an increase, and “−” for a decrease

🛎️ Calculating Percentage Increase and Decrease

  • Increase: 60 increased by 20% = 60 × (1 + 20%) = 60 × 1.2 = 72
  • Decrease: 90 with 30% off = 90 × (1 − 30%) = 90 × 0.7 = 63

🛎️ Finding the Original Value (Reverse Percentage)

  • Use the same formula, but the original value is the unknown
  • Solve it by dividing (e.g. original × 0.6 = 36, so original = 36 ÷ 0.6 = 60)

Practice Questions

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Interactive Activity

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