1. Converting Fractions to Decimals
Lesson 5.2
AMSTI 2006

2. Video
Lets watch a video to preview how to convert fractions to decimals, the Egyptian way!

4. Converting Fractions to Decimals
To convert a Fraction to a Decimal manually, follow these steps:
Step 1: Find a number you can multiply by the bottom of the fraction to make it 10, or 100, or 1000, or any 1 followed by 0s.
Step 2: Multiply both top and bottom by that number.
Step 3. Then write down just the top number, putting the decimal place in the correct spot (one space from the right for every zero in the bottom number)

5. Method #1: Converting with Proportions
Example # 1: Express 3/4 as a Decimal
Step 1: We can multiply 4 by 25 to become 100
Step 2: Multiply top and bottom by 25
3 = 75

6. Example # 1 continued….
Step 3: Write down 75 with the decimal place 2 spaces from the right (because 100 has 2 zeros);
Answer = 0.75
Can you explain what we just did?
Try to express ¼ as a decimal using method # 1.

7. Method #2: Convert by Dividing
Example #1: to write 5/8 as a decimal, we need to calculate 5 ÷ 8:
8 √ 5.000
So = as a decimal.
Try this example: write 4/5 as a decimal using division (method #2).

8. Remember…
To change a fraction to a percentage follow the rules for fraction to a decimal and then multiply by 100.
Or use the magic square!
Cross multiply 
Part
Variable
Whole
100

9. Lets Practice!!
We are going to use this website to fish out some fractions and decimals.
Lets see how well you understand this lesson.
Go to
Select “Math” in the left margin
Select “Fishy Fractions”
Select “Fractions and Decimal Match”