A percentage is a special way of describing a part of something. A percentage is a number that represents a fraction of 100 parts. Thus, 100% means the whole total of whatever is being measured, while 50% is the half. When you learn how to write percentages, multiplication and other calculations become easy on a calculator. Some calculators even have a % button which makes calculations even easier.
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Method 1 of 4: Converting Fractions and Decimals to Percentages
Step 1. Review the general meaning of fractions
A fraction is a comparison between two numbers, usually representing the part of something to the total. A common example is a pie cut into, say, eight equal parts. The number above, called the numerator, represents the number of the selected part. The number below the fraction, named the denominator, represents the sum of all the pieces of the pie. - in this case, is 8.
- For example, the fraction 1/8 means one part of a pie cut into 8.
- The 7/8 fraction represents 7 pie portions out of a total of 8 portions.
Step 2. Identify the special relationship of percentages
Percentages are unique fractions whose denominator is always 100. While the analogy of a pie cut into 100 equal pieces is unrealistic, the concept of percentage is very useful thanks to this standard.
Find Half
For fractions, the size of the "half" of something will depend on total number of parts.
If the pie is cut into 8 pieces, it means half is 4. However, if the pie is cut into 22 pieces, it is 11. The target is always changing. However, for fractions, half always equals 50%.
Step 3. Use a calculator to convert any fraction to a decimal number or percentage
If you're given a fraction, you can easily convert it to a decimal number using a calculator. Remember that fractions reflect division, and use a calculator to divide the numerator by the denominator. The calculator will return the result as a decimal number.
Examples to Try in the Calculator
Say you have the fraction. On the calculator, do the calculation 1 2, and the calculator will return 0.5.
Convert the fraction 1/4 by calculating 1 4. The result is 0.25.
For a more challenging example, you can convert the fraction 274/312 by calculating 274 312. The result is 0.878. (rounded up to three decimal places for convenience.)
Step 4. Convert the decimal to a percentage by shifting the location of the comma in the number
If you have a number that is already a decimal, converting it to a percentage is very easy. Since the decimal numbering system is based on a factor of 10, you can convert a decimal number to a percentage simply by shifting the decimal point two digits to the right, then adding the % symbol at the end. if the decimal number consists of only one digit, add a 0 to the right of the number, for example, 0.5 is changed to 0.50 or even 0.500. The value of all the numbers is the same.
Example
Say for example the fraction is 1/2, which converts to a decimal is 0.5. To convert it to a percentage, shift the decimal point two digits to the right. First, adjust 0.5 to 0.50. Then, move the decimal point and put the % symbol at the end so that 0.50 is now 50%.
For the example of the fraction 1/4, where the decimal number is 0.25, it can be directly converted into a percentage by shifting the decimal point, which is 25%.
Step 5. Memorize basic fractional conversions
It can be useful if you can memorize the percentages of certain basic fractions. Since the denominator of a percentage is always 100, certain values are constant.
Some Basic Conversions to Know
3/4 = 75%
1/2 = 50%
1/3 = 33 1/3%
1/4 = 25%
1/5 = 20%
1/8 = 12.5% (commonly used in banking)
Method 2 of 4: Performing Basic Calculations Using Percentages
Step 1. Add the percentage directly
Since all percentages reflect the same denominator (100), it is possible to add up all percentages directly. Remember when adding two fractions, you have to make the denominators the same first. For fractions, the denominators are all the same, so all you have to do is add up the numbers.
Example of Addition of Percentages
You can calculate the contribution of multiple shareholders by adding up the relative percentages of their shareholdings. For example if the shareholding percentages of 6 shareholders are 10%, 5%, 8%, 22%, 10% and 8% respectively, simply add up 10+5+8+22+10+8 = 63. The contributions of the six people were 63% of the company's total shares.
When adding, ignore the percentage symbol, and write only numbers. Return the % symbol in the final answer.
Step 2. Subtract the percentage in the same way
Again, since all percentages reflect the same denominator (100), the calculation can be done directly. If the question asks you to subtract a certain part from a whole thing, use the number 100 because the whole thing equals 100%.
Percentage Subtraction Example
Say you want to calculate a percentage of earnings. 100% means the entire income from a project, but there are deductions, for example 10% for costs, 12% for salaries, and 25% for taxes. How much is left? You just need to use a calculator to calculate 100-10-12-25 and get 53%.
Step 3. Multiply or part using decimal numbers
If there is a question that multiplies a percentage by a whole number, for example 25% x 30, convert 25% to its decimal number (0.25) and do the calculations. Thus, the question becomes 0.25 x 30 which produce 7, 5.
Similarly, if you find a division problem, for example 200 ÷ 10%, convert the percentage to a decimal which results in 200 ÷ 0, 10; the rest you can calculate on a calculator. The result is 2,000.
The final result may seem surprising because division usually results in a number that is smaller than the number that was divided. However, when divided by a fraction, a number is multiplied by the reciprocal of the fraction so that the result is always greater. For example, a number divided by 1/10 is the same as being multiplied by 10. A number divided by 1/2 is equal to being multiplied by 2
Method 3 of 4: Calculating Percentage of Integers
Step 1. Multiply to find the percentage “of” a number
A common calculation for percentages is to find the percentage “of” another number. For example, if you eat at a restaurant and want to tip 15% of the total bill. When calculating percentages, the word “from” has the same meaning as “times” or “multiplication.” Thus, 15% "of" 100, for example, means 15% x 100.
Step 2. Convert the percentage to a decimal number and multiply
To calculate a percentage of a whole number, you need to convert the percentage to a decimal number, as described above. Then, simply multiply the numbers.
Example of Finding Percentage of an Integer
To find 15% of 100, change 15% to 0.15. Then, multiply 0.15 x 100, and get 15.
Step 3. Write down the result without the percentage symbol
When you search for a whole number percentage, the result is a whole number and not a percentage. You might start with a percentage symbol, but then convert the percentage to a decimal number before multiplying so that the result no longer has the percentage symbol.
In this example, 15% of 100, is the whole number 15
Method 4 of 4: Using the % Key on the Calculator
Step 1. Look for the % button on the calculator
Most simple calculators have a button with the symbol %. More advanced calculators, such as graphing calculators, do not have this button because the manufacturers assume you can calculate it without it. However, many basic calculators do.
Step 2. Experiment with the % key for decimal conversion
The easiest way to use the % key is to convert the number from its percentage form to a decimal number. Just enter a number and press the % key, then the calculator will show you the decimal number.
Example Using the % Button
To make the number 4% on the calculator, simply press the 4 key, then the %. The calculator will convert the number 4 to 0.04, which is the decimal form of 4%.
To convert 82.5% to a decimal, simply press the 8, 2,., 5, %. The calculator will display the number 0.825.
Step 3. Use the % button to calculate
The % button on the calculator makes some calculations easier. Say you want to calculate the tip amount, and want to know 15% of the total bill of IDR 75,320. If you have a calculator, calculate 15% x 75, 32 to get 11,298. Thus, the tip is IDR 11,300.
- When you use the calculator to calculate percentages, be sure to press C (Clear) or AC (All Clear) before starting.
- When you enter the numbers in this calculation, you will notice that when you press the % key, the number 15 changes to.15 (equal to 0.15). The calculator will continue calculating.15 x 75, 32.
