Mastering Percentages: Comparing Parts of a Whole

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• Mathematics
• Primary Education

Mastering Percentages: Comparing Parts of a Whole

What do you already know about percentages?

Learning Objective

LO: To understand and use percentages to solve problems.

Flashback

1. What is the value of the digit 7 in the number 3,745?

2. Solve: 36÷4

3. Convert this fraction to a decimal: 1/2

4. What is the perimeter of a rectangle with sides 5 cm and 3 cm?

Flashback

1. What is the value of the digit 7 in the number 3,745?

2. Solve: 36÷4

3. Convert this fraction to a decimal: 1/2

4. What is the perimeter of a rectangle with sides 5 cm and 3 cm?

700

Flashback

1. What is the value of the digit 7 in the number 3,745?

2. Solve: 36÷4

3. Convert this fraction to a decimal: 1/2

4. What is the perimeter of a rectangle with sides 5 cm and 3 cm?

700

9

Flashback

1. What is the value of the digit 7 in the number 3,745?

2. Solve: 36÷4

3. Convert this fraction to a decimal: 1/2

4. What is the perimeter of a rectangle with sides 5 cm and 3 cm?

700

9

0.5

Flashback

1. What is the value of the digit 7 in the number 3,745?

2. Solve: 36÷4

3. Convert this fraction to a decimal: 1/2

4. What is the perimeter of a rectangle with sides 5 cm and 3 cm?

700

9

0.5

16 cm

What is a Percentage?

A percentage shows a part out of 100. For example, 75% means 75 out of 100.

Percentages as Fractions

Percentages can be written as fractions. 50% is the same as 50/100 or 1/2.

Percentages as Decimals

To write a percentage as a decimal, divide by 100. For example, 25% = 0.25.

Why Use Percentages?

Percentages help us compare numbers, track progress, and understand information clearly.

Everyday Percentages

We use percentages in sales, tests, battery levels, and sports scores.

Finding 50% of a Number

50% means half. Find 50% by dividing by 2. Example: 50% of 20 is 10.

Finding 25% and 75%

75% is 3/4. Divide by 4 then multiply by 3. Example: 75% of 20 = 15.

75%

25%

Find 25% by dividing by 4. Example: 25% of 20 = 5.

How to Find 10% and 20%

10% is one-tenth. Divide by 10. 20% is 10% × 2.

Linking Fractions, Decimals, & Percentages

Decimal

Fraction

1/2 = 0.5 = 50% 1/4 = 0.25 = 25% 3/4 = 0.75 = 75%

0.2 = 1/5 = 20% 0.1 = 1/10 = 10%

Percentages in Shopping

When you see "20% off", the price is reduced by 20% of the original price.

Percentages in Technology

Battery icons show how much charge you have left as a percentage.

Percentages in School

Test scores are often given in percentages. 80% means 80 correct answers out of 100.

Words for Percentages

Per Cent

Percent, percentage, percent sign.

Per cent means "per hundred". Symbol: %

Common Terms

Practice Question #1

What is 50% of 30?

Practice Question #2

Find 25% of 40.

Practice Question #3

If a shirt costs £20 and has a 10% discount, how much do you save?

Quick Recap

Percentages help compare and understand parts of a whole. They connect to fractions, decimals, and real life.

Reflection

Think of a time you used percentages this week. Where did you see them, and what did they mean?

Write down 3 things you learned in this lesson.

Write down 2 things you want to know more about.

Ask 1 question about something you haven't quite understood yet.