📈 Percentages

Percent Means "Per Hundred"

The word percent comes from Latin per centum — per hundred. 35% means 35 out of every 100. To convert to a decimal, divide by 100: 35% = 0.35. To convert a decimal to percent, multiply by 100: 0.7 = 70%.

Fraction → Percent: divide and multiply by 100. 3/4 = 0.75 = 75%.

Finding a Percent of a Number

Three methods — all equivalent:

• Decimal method: 30% of 80 = 0.30 × 80 = 24
• Fraction method: 30% = 30/100 = 3/10 → 80 × 3/10 = 24
• Proportion method: 30/100 = x/80 → 100x = 2400 → x = 24

Percent Increase and Decrease

Percent change = (new − original) / original × 100. A positive result is an increase; negative is a decrease. A price rises from $80 to $100: (100 − 80) / 80 × 100 = 25% increase.