Lesson 2: Decimal Fractions – Understanding and Using Decimals

📥 Introduction

Have you ever handled money, like paying GHS 5.75 for snacks or measuring 2.5 liters of water? If so, you were already working with decimals without even thinking about it!
Decimals are simply another way to show fractions or parts of a whole. They are everywhere in everyday life — in shopping, sports scores, banking, science experiments, and more.

In this lesson, you’ll learn how decimals work, how to perform operations with them, and how to switch between fractions and decimals easily!

🧠 Key Concepts and Explanations

1. What is a Decimal?

A decimal is a number that has a whole number part and a fractional part, separated by a decimal point.

Example: In 7.3, the “7” is the whole number, and “0.3” is the fractional part (3 tenths).

2. Place Value in Decimals

Each digit after the decimal point has a special place value:

Example: In 5.327:

• • 3 is in the tenths place:

• • 2 is in the hundredths place:

• 7 is in the thousandths place:

3. Converting Between Fractions and Decimals

Fractions and decimals are two ways to show parts of a whole. You can convert easily between them:

• To change a fraction to a decimal: divide the numerator by the denominator.
• To change a decimal to a fraction: read the decimal value according to place value and simplify.

Examples:

Convert to a decimal:

3 ÷ 4 = 0.75

Convert 0.6 to a fraction:

0.6 =

4. Basic Operations with Decimals

📝 Step-by-Step Sample Walkthroughs

Example 1: Add 2.45 and 3.6

• Line up decimals: 2.45 + 3.60
• Add: 6.05

Example 2: Multiply 0.5 × 0.2

• Ignore decimals and multiply: 5 × 2 = 10
• Two decimal places total, so: 0.10

Example 3: Divide 3.6 ÷ 0.6

• Move decimal to make 0.6 a whole number (×10):
• 3.6 becomes 36 and 0.6 becomes 6.
• Now divide: 36 ÷ 6 = 6

✅ Practice Exercises

A. Convert Between Fractions and Decimals

• = ?
• 0.75 = ?
• = ?

B. Add, Subtract, Multiply, Divide

• 4.25 + 1.6 = ?
• 5.2 – 2.35 = ?
• 0.8 × 0.4 = ?
• 7.2 ÷ 0.3 = ?

C. True or False?

• • 0.25 is the same as .

• 0.8 is the same as .

D. Word Problems

1. A bottle contains 2.5 liters of water. If you drink 0.75 liters, how much water is left?
2. Adjoa bought fruit for GHS 8.50 and a drink for GHS 2.75. How much did she spend altogether?

🔁 Recap

• Decimals show parts of a whole, separated by a decimal point.
• Understand place value to work with decimals easily.
• Convert between fractions and decimals by dividing or reading place values.
• Always line up decimal points when adding or subtracting.

🪞Reflection Prompt

Look at the money you have right now. Can you write down the total using decimals? How would you explain that total as a fraction?