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Percentage Change Formula
Financial Math • Grades 6, 7, 8, 9
Financial Math
Percentage Change Formula
Calculate percent increase, percent decrease, and relative change with ((New - Old) / Old) × 100%.
The Formula
Δ% = ((New - Old) / Old) × 100%
Used for: Calculating percentage increase, percentage decrease, and relative percentage error
Δ%Percentage change (% increase or decrease)
OldOriginal / initial starting value
NewFinal / ending value
⚡Live Interactive Quick Solver
Instant Calculation📈 Percentage Change:25.00% Increase
Formula: ((100 - 80) / |80|) × 100% = +25.00%
\Delta \% = \frac{\text{New} - \text{Old}}{\text{Old}} \times 100\%✨ Free Classroom Assessment ToolSet A & Set B Anti-Cheat
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🎯 Key Concepts & Rules
Essential principles for calculating with this formula:
📊
Δ% = ((New - Old) / Old) × 100%Difference divided by initial original value.
📈
Positive = Increase, Negative = DecreaseSign indicates direction of change.
📝 Worked Examples & Step-by-Step Solutions
Example 1: Price Increases from $50 to $65
Problem:
Old = 50, New = 65.1
Difference
New - Old = 65 - 50 = 152
Divide by Old
15 / 50 = 0.303
Percentage
0.30 × 100% = +30% IncreaseAnswer: +30% Increase
💡 Pro Tips & Common Mistakes
Always Divide by Old Value
The most common student mistake is dividing by the new value instead of the original.
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