To quickly find the multiplier for any percentage change:
- For a P% \textbf{increase}, the multiplier is \(1 + \frac{P}{100}\).
- For a P% \textbf{decrease}, the multiplier is \(1 - \frac{P}{100}\).
For example, a 15% decrease would have a multiplier of \(1 - 0.15 = 0.85\).