PU L12
M8 L12
Decimal Numbers
Objectives
• I can…
• Understand the relationship between place values and the function of
the decimal point.
• Write decimal numbers using words.
• Compare and order decimal numbers.
• Convert between fractions, decimal numbers and percents.
• Compare and order different forms of rational numbers.
• Convert between forms of rational numbers to solve problems.
New Concepts
• Our number system is a base ten system. Why?
• When we use words to describe a decimal number, read left to right
with the word “and” at the decimal point.
Example 1
• Hw #5
• Use words to write 4.02
• Four and two hundredths.
Example 2
• Hw #23
• Arrange from least to greatest.
•
1
−0.12, −1.2, −
2
↑
−0.5
→ −1.2, −0.5, −0.12
• Each decimal can be expressed as a fraction.
• 12.25 =
25
12
100
=
1
12
4
Example 3
• Hw #7
• Convert 0.17 to a fraction.
• 0.17 =
17
100
Example 4
• Write 0.05 as a fraction
5
100
=
1
20
• To express a fraction or mixed number as a decimal, we divide.
Example 5
• Hw #6
5
8
• Write as a decimal.
• 0.625
Example 6
• Write
3
3
8
as a decimal.
• 3 + 0.375 = 3.375
• When converting a rational number to a decimal we have three
outcomes.
• 1. The rational number is an integer.
• 2. The rational number is a terminating decimal number.
• 3. The rational number is a non-terminating decimal number w/
repeating digits.
1
3
• =
1
3
= 0.3333
• To convert a number to a percent, multiply by 100%.
• Convert to percents.
• A) 0.2 → 0.2 × 100% = 20%
• B) 0.125 → 0.125 × 100% = 12.5%
• C) 1.5 → 1.5 × 100% = 150%
• Convert a percent to a decimal.
•
•
350
350% =
= 3.5
100
75
75% =
= 0.75
100
Example 8
• Hw #8
• How much money is 15% of $60.
• 15% =
15
100
= 0.15
• 0.15 × $60 = $9.00
• $9.00
Assessment
• HW L12 #1-30, p.83-84
• Help w/ 4, 9, 10, 24-26, 30