1. Calculations with Percents
45% 8%
12%
Calculations with Percents
36%
90%
10%
.7%
64%
85%
57%

2. Review: Change a fraction to a decimal:
Divide the numerator by the denominator.
Example: Change 5/9 to a decimal.
5 ÷ 9 means
5/9 = 0.55 or 0.56
0.5 5 5
-45 5
-45 5

3. Review: Change a decimal/number to a percent:
Move the decimal two places to the right. (Multiply by 100).
Example: Change to a percent.
0.683(100) = 68.3%
Change a percent to a decimal/number:
Move the decimal two places to the left. (Divide by 100).
Example: Change 3% to a decimal.
3 ÷ 100 = 0.03

4. You cannot do any math problems with percents
You cannot do any math problems with percents. You must change the percent to a decimal.

5. Finding a Percent of a Number
What is 25% of 32?
Step 1: Change English to Math.
What is your variable
IS is your = sign
Change your percent to a decimal
OF means multiply
x = .25(32)
Step 2: Decide how to solve the problem, then solve.
x = 8
8 is 25% of 32.

6. Finding the Percent One Number is of Another
What percent of 120 is 90?
Step 1: Change English to math.
What is your variable
OF means multiply
IS is your = sign
x(120)=90
Step 2: Decide how to solve the problem, then solve.
x = 90÷120 = 0.75
Step 3: Change your answer to a percent.
x = 75% 75% of 120 is 90.

7. Finding a Number when the Percent is Known
36 is 4% of what number?
Step 1: Change English to Math.
IS is your = sign
Change your percent to a decimal
OF means multiply
What is your variable
36 = 0.04(x)
Step 2: Decide how to solve the problem, then solve.
36÷ 0.04 = x
x = 900
36 is 4% of 900

8. Practice: 2.64 10% 128 What number is 44% of 6?
125 is what percent of 1250?
32 is 25% of what number?
2.64
10%
128