3.
Decimals: Definition
Decimal: From the Latin decimalis, meaning tenths.
Root is Latin decim, ten.
English: Decade, December?
A decimal is a fraction with a denominator
that is a multiple of 10.
4.
Vocabulary: Per Cent
Percent: From the Latin per centum. Per: for each as in "One
per student.‛ Centum: hundred Century, Cent, Centimeter,
Centipede
5% = 05 = 1 = .05
100% = 100 = 1
100 20
100
**Fractions, Decimals, & Percents are three different ways of
expressing the same amount. All three show a single number
based on the relationship (ratio) between two other
numbers.
5.
Decimals: Reading & Writing
Reading
Read the whole number on the right
2. Read the decimal point as the word ‚and‛
3. Read the decimal fraction on the right
Example: 8.3 = ‚eight and three tenths‛
4.06 = ‚four and six hundredths‛
0.5 = ‚five tenths
The word ‘point’ is not a number and is not
used when reading decimals.
1.
Each decimal expression with a value less than 1 is
preceded by a leading zero to emphasize the presence of
a decimal. For example, .7 is correctly written as 0.7
7.
Fractions
Decimals
Percent
Since the % sign cannot be +, -, x, ÷; numbers expressed as
percents must be changed to a decimal or fraction before
any calculations can be made.
A. To change a decimal to a percent: Move the decimal 2
places to the right and add the % sign.
B. To change a percent to a decimal: Move the decimal 2
places to the left and drop the % sign.
C. To change a fraction to percent, or percent to fraction,
the number must be changed to a decimal first.
8.
Class Notes: Converting Fractions
Decimals
There are 3 ways to change fractions to decimals:
1. If the denominator is 10, 100, 100, etc., you can
change to a decimal right away.
Example: 4/10 = .4, 4/100 = .04, 4/1000 = .004
2. If the denominator is a factor (divides evenly) of
10 or 100, multiply the top and bottom by the
number needed to reach 10 or 100.
Example 1: 1/5; 5x2 =10, multiply both by 2 to get
2/10, which is .2
Example 2: 16/25; = ?,
9.
Class Notes: Converting Fractions
Decimals
3. If the denominator is not a factor of 10 or 100, your last
option is to divide the numerator by the denominator. The
denominator goes into the numerator. You can always find
the decimal form of a fraction by doing this
10.
Class Notes: Converting Decimals
Fractions
Converting Decimals to Fractions or Mixed Fractions
The number of digits in the decimal will tell you what the
denominator is before you simplify.
Example 1: .65 is sixty five-hundredths, which is 65/100
Use the GCF to Simplify
Divide by 5 to get the simplified fraction of 13/20
Ex. 2: .065 is what fraction? sixty five-thousandths; 65/1000
Use the GCF to simplify
Divide by 5 to get the simplified fraction of 13/200
Ex. 3: 2.55 = Write the non-simplified fraction.
Simplify Simplify to get 2 11/20
2 55/100
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