1. Name __________________________________________ Date ____________
Polizzi/Woska Math – 6
Study Guide
Math Test
Percents
Topics on Test:
1. Percent to Decimal 6. Finding percent of a number with decimals
2. Percent to Fraction 7. Tax
3. Fraction to Percent 8. Tip
4. Decimal to Percent 9. Discount
5. Finding percent of a number with proportions
 Percent to Decimal
To change a percent to a decimal, divide the percent by 100  move decimal two places to the left
14% = .14 45% = .45 3% = .03 36.2% = .362
 Percent to Fraction
To change a percent to a fraction, write the percent as a numerator and 100 as denominator,
then simplify to lowest terms
99 50 1 42 21
99% = 50% = = 42% = =
100 100 2 100 50
 Fraction to Percent
To change a fraction to a percent, divide the numerator by the denominator, then move the decimal two
places to the right. Or, when possible, change the fraction to make a denominator of 100, the percent is
now the numerator.
5 7 70 2
= 5  8 = 0.625 = 62.5% = = 70% = 2  5 = 0.4 = 40%
8 10 100 5
 Decimal to Percent
To change a decimal to a percent, move the decimal two places to the right.
0.65 = 65% 0.03 = 3% 1.09 = 109% 0.8 = 80%

2.  Finding percent of a number with proportions
To find the percent of a number using proportions, see how many times the denominator can go into
100 (divide) and multiply the numerator by that amount. The new numerator is your percent.
5
5 x 5 25
= step 1: 20 100 step 2: 5 x 5 = 25 So, = = 25%
20 100 20 100
 Finding percent of a number with decimals
To find percent of a number using decimals, turn the percent into a decimal and multiply by the whole
number.
80% of 40 .80 = 32 75% of 480 .75 = 36
x 40 x 480
32.0 0
600
+ 3000
36.00
 Tax
To find tax, turn the percent (we usually use 8% for tax in class) into a decimal and multiply by the
dollar amount. Then, add that answer to the original dollar amount.
Find the tax on an item that costs $21.00.
21.00 21.00
x .08 The tax is $1.68. + 1.68 The total cost will be $22.68.
1.6800 22.68
 Tip
To find tip, you use the same method that you would for finding tax. Turn the percent into a decimal
and multiply by the dollar amount. Then, add that answer to the original dollar amount.
If you wanted to tip your server 15% on a bill that is $32.50, how much would you be spending on your
dinner?
32.50 32.50
x .15 The tip will be $4.88. + 4.88 The total amount you will spend is $37.38.
16250 34.45
+ 32500
4.8750
 Discount
To find discount, turn the percent into a decimal and multiply by the dollar amount. Then, subtract
your answer from the original dollar amount.
A shirt that costs $38.00 is on sale for 20% off. How much will you spend?
38.00 38.00
x .20 The discount will be $7.60. - 7.60 The total cost will be $30.40.
7.6000 30.40