Ratio & ProportionDeep Dive
The Multiplier Method Explained
Part of Percentage Decrease — GCSE Mathematics
This deep dive covers The Multiplier Method Explained within Percentage Decrease for GCSE Mathematics. Revise Percentage Decrease in Ratio & Proportion for GCSE Mathematics with 12 exam-style questions and 22 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 3 of 5 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 3 of 5
Practice
12 questions
Recall
22 flashcards
📊 The Multiplier Method Explained
Step-by-Step Process
- Identify the percentage decrease
- Convert to decimal: percentage ÷ 100
- Subtract from 1: 1 - decimal = multiplier
- Multiply original by multiplier
Why Subtract from 1?
When we decrease by 25%, we want:
- Original amount (100%) - Removed amount (25%) = 75%
- 75% = 0.75 as a decimal
- So multiplier = 1 - 0.25 = 0.75
Common Multipliers
| Decrease | Multiplier | Calculation |
|---|---|---|
| 5% | 0.95 | 1 - 0.05 |
| 10% | 0.90 | 1 - 0.10 |
| 15% | 0.85 | 1 - 0.15 |
| 20% | 0.80 | 1 - 0.20 |
| 25% | 0.75 | 1 - 0.25 |
| 30% | 0.70 | 1 - 0.30 |