The formula
Percent change = (new − old) ÷ old × 100
- Positive result → increase
- Negative result → decrease (often reported as an absolute “% decrease”)
Examples
Increase: 50 → 65
(65 − 50) ÷ 50 × 100 = 30% increase.
Decrease: 80 → 60
(60 − 80) ÷ 80 × 100 = −25% (a 25% decrease).
Price markup
Item costs $40, sells for $55: (55 − 40) ÷ 40 × 100 = 37.5% markup.
Skip the hand math.
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