20% of 500.

**The reasoning** "20% of 500" means "20 per hundred of 500" — or mathematically, 20/100 × 500. Here's the working: - 20% = 20/100 = 0.2 - 20% of 500 = 0.2 × 500 = **100** **Quick method:** 10% of any number is just that number ÷ 10. So 10% of 500 = 50. Since 20% is double of 10%, then 20% of 500 = 50 × 2 = **100**. **Why the wrong options tempt you** - **Option A (50):** This is 10% of 500, not 20%. You might divide by 10 but forget to double it. - **Option C (150):** This would be 30% of 500. Perhaps you miscalculated 20 + 10 somewhere. - **Option D (200):** This is 40% of 500. Maybe you doubled twice by accident, or confused "20% of 500" with "500 minus 20%." **Quick takeaway** To find any percentage: convert to a decimal (move the decimal point two places left), then multiply — so 20% always means "multiply by 0.2."