Grade 6 (age 11-12)

Percentage

A percentage tells you how big a part is when the whole is set to 100, and we write it with the percent sign (%). You divide the part by the whole and multiply by 100, so getting 15 of 20 questions right is 75%. From test scores and store discounts to today's humidity, percentages turn up all around daily life. Here you can color a grid of 100 cells and change the part and the whole to see how the percentage shifts.

What is Percentage?

💡 Compare Against 100

①Percentage is the ratio with the whole set to 100

②25% = 25 out of 100

③Used widely (test scores, discounts, humidity)

Percentage45%

Calculating Percentage

Part35

Whole100

📊 How to Calculate

①Percentage = (part ÷ whole) × 100

②Example: 5 of 20 = (5÷20)×100 = 25%

③Convert: fraction → decimal → percentage

Summary

Percentage Formula

Percentage(%) = PartWhole × 100

Size of part when whole is 100

Fraction → Percentage

34 = 0.75 = 75%

Convert fraction to decimal, multiply by 100

🎯 Key Points

①Percentage = (part÷whole)×100

②50% = half, 25% = 1/4, 75% = 3/4

③30% off → pay 70% of original

④Percentages allow comparison across different bases

⑤Decimal → percentage: ×100; percentage → decimal: ÷100

Examples & Unit Review

Example 1

You answered 15 out of 20 questions correctly. What is the accuracy as a percent?

Percent = (part ÷ whole) × 100 = (15 ÷ 20) × 100.

0.75 × 100 = 75%.

▸ 75%

A percent is the rate when the reference amount is taken as 100.

Example 2

A bag listed at 8000 won is 20% off. How much is the discount?

Discount = price × rate = 8000 × 20/100.

8000 × 0.2 = 1600 won off.

▸ 1600 won

To compute a percent, divide by 100 to get a decimal (or fraction) and multiply.

Unit Review

Out of 50 people, 30 agreed. What is the approval rate as a percent?

①60%

②30%

③50%

④20%

▸ ① 60%

Percent = (agreed ÷ total) × 100 = (30 ÷ 50) × 100.

0.6 × 100 = 60%.

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