Percentages: Fractions, Decimals & Percents
Week 5 · Percentages
Master converting between fractions, decimals, and percents, and learn to find the percent of any number.
What is a Percent?\nA **percent** means "out of 100." The symbol is **%**.\n25% means 25 out of 100, or 25/100, or 0.25.\n\n## Converting Between Forms\n**Fraction to Percent:** Divide numerator by denominator, then multiply by 100.\n- 3/4 = 3 / 4 = 0.75 = **75%**\n\n**Decimal to Percent:** Multiply by 100 (move decimal two places right).\n- 0.4 = **40%**\n\n**Percent to Decimal:** Divide by 100 (move decimal two places left).\n- 35% = **0.35**\n\n## Finding the Percent of a Number\nMultiply the percent (as a decimal) by the number.\n\n**What is 30% of 50?**\n- Convert: 30% = 0.30\n- Multiply: 0.30 x 50 = **15**\n\n## Finding What Percent One Number is of Another\nDivide the part by the whole, then multiply by 100.\n\n**9 is what percent of 36?**\n- 9 / 36 = 0.25\n- 0.25 x 100 = **25%**
Worked Examples
Example 1
📝 Convert 2/5 to a percent.
✓ Answer: 40%
2 / 5 = 0.40. Multiply by 100: 0.40 x 100 = 40%.
Example 2
📝 What is 15% of 200?
✓ Answer: 30
Convert 15% to a decimal: 0.15. Then multiply: 0.15 x 200 = 30.
Common Mistakes to Avoid
- ⚠️Moving the decimal the wrong direction — to convert percent to decimal, divide by 100 (move left)
- ⚠️Forgetting to convert the percent to a decimal before multiplying
- ⚠️Mixing up the part and the whole when finding what percent one number is of another