Pre Algebra (Period 2 & 4)

Fractions, Decimals & Percents 6-5

Fractions = Decimals = Percents!!
A percent is a ratio that compares a number to 100.
Therefore you can write a percent as a fraction with a denominator of 100

Percent means "per hundred" or "out of a hundred"
THe symbol % comes from the fraction bar and a denominator of 100

TO CHANGE ANY % TO A FRACTION:

simply get rid of the % sign and put the number over a denominator of 100
Simplify
5% = 5/100 = 1/20

TO CHANGE ANY % TO A DECIMAL

Simply get rid of the % and move the decimal point over to the LEFT-TWO PLACES
( its running away from the %... it is so sad that the % sign went away!!)
5% = 0.05

TO CHANGE ANY DECIMAL TO A %
Simply put the % to the right of the number and move the decimal point to the RIGHT TWO PLACES ( the decimal is so happy to see the percent sign -- it runs toward it!!)

0.245 = 24.5%

TO CHANGE ANY FRACTION TO A %
Simply change it to a decimal first, then follow as above

20/50 = 2/5 = 0.4 = 40%
But this one is a good one to think of changing 20/50 = 40/100 and then easily seeing 40%

If the denominator will go into 100 easily, you can use equivalent fractions!!(as in this case)

If you ever forget how many places to move the decimal, just look at the % sign-- It tells you 2 places ( 2 zeros)

You need to know a few percentages
10%--> just move the decimal point one place to the LEFT. That's it
$75.00 with a 10% discount
The discount would be $7.50

On $80.00 the 10% discount would be $8.00 and a 5% would be half of that or $4.00

You can find %20 easily as well-- just double 10%

Know
50% --> 1/2
25% --. 1/4
75% --> 3/4