themathlab.com

 350 Converting a Percent to a Decimal or a Fraction

 How to convert the "devil remover notation of %" and create a usable number

 a fraction capable calculator may be helpful

We know from lesson 340 A history of Percents, the word "percent" originally meant "cents", and was used back in the dark ages by merchant to remove evil spirits form numbers.

Unfortunately, since a % sign is nothing more than an 'evil spirit remover', we must convert any % numbers into either decimals or fractions before we can use them.

HOW TO WRITE A PERCENT AS A DECIMAL:

Since the word "percent" originally meant "cents", changing a percent to a decimal is easy; just write it as money in dollar notation, and then remove the dollar sign.

Let's look at a few:

1. 35% or 35 cents = \$.35 or 0.35 (Some people put the zero in front of the decimal to draw attention to the decimal.)
2. 8% or 8 cents = \$.08 or 0.08
3. 150% or 150 cents = \$1.50 or 1.50=1.5
(Remember the zero in the hundredths spot of the decimal can be dropped without changing the value.)

*NOTICE that in every case the decimal notation places the decimal point 2 spots to the LEFT of the % notation.

This actually ALWAYS HAPPENS. To change a % to a decimal, simply drop the percent sign and move the decimal two spots left.

NOTE: If you don't see any decimal point on a percent number, like in the examples above, remember that it is always to the right of the one's place. For example, 35%=35.%.

Let's look at a few harder ones:

1. 3.5% or 3.5 cents = \$.035 or 0.035
2. .5% or .5 cents or half a cent =\$.005 or 0.005
3. 4,521% or 4521 cents = \$45.21 0r 45.21
4. 68 3/5% or 68.6 cents* = \$.686 or 0.686
*Notice that above 3/5 =.6, so we just changed the original % to a decimal before getting dollar

HOW TO WRITE A PERCENT AS A FRACTION:

Now that you can write percents as decimals, to get the fraction you simply say the decimal formally.

For example:

1. 35% = 0.35 which is read, "thirty-five hundredths", so we write the fraction 35/100. Now this will reduce to 7/20, so 35% = 7/20.
2. 752% =7.52 which is read, "seven and fifty-two hundredths", so we write the mixed number 7 52/100. This will reduce to 7 13/25.
3. .24% = 0.0024 which is read,
"twenty-four ten-thousandths", so we write the fraction
24/10,000. This fraction reduces to 3/1,250.

 What is 45% as a decimal and as a fraction? (answer) Give the fraction and decimal for 250%. (answer) Write 3 1/2% as a decimal and a fraction. (answer)

340 The History of Percent

360 set up a proportion to solve % problems

370 set up an equation to solve percent problems

The Customizable Percent Test

 About Us | Algebra | Contact Us | Dictionary | Games | Geometry | Gym | Humor | Lab | Magic | Natural Math | PreAlgebra | Resources | Teachers Only | Toolbox | TreasureFinder | Wonders | Writings