Knowing how to convert numbers into percentages, fractions and decimals is one of the basic math skills that it is essential to acquire. Once learned, the concept behind the conversion process will become easy to master and use. Learning how to quickly convert the small numbers of everyday use will be of great help to you both in school tests and in financial calculations.
Steps
Method 1 of 3: Converting the Percentages
Step 1. To convert a percentage to a decimal number, move the separator (the comma) two places to the left
Unless otherwise indicated, a percentage has the decimal separator after the last number. For example, the percentage 75% can also be correctly expressed in the form 75.0%. Moving the decimal separator two places to the left converts the percentage to a decimal number. This is the same result as dividing the same number by 100. Here are some examples:
- 75% converted to a decimal number becomes 0.75;
- 3, 1% converted to a decimal number becomes 0, 031;
- 0, 5% converted to decimal number becomes 0, 005.
Step 2. Express a percentage as a fraction of the number 100
This is another correct way to express a percentage number. The percentage coefficient is transformed into the numerator of the fraction, while 100 becomes the denominator. At this point, where possible, proceed by simplifying the fraction obtained to a minimum.
- Example: the 36% percentage can be written as 36/100.
- To simplify the terms of the fraction, it is necessary to identify the greatest common divisor, that is, the largest number capable of dividing the numerator and denominator of the fraction (36 and 100). In this case it is number 4.
- By performing the calculations the result we will get will be 9/25.
- To check if the result obtained is correct, divide the numerator of the fraction by the denominator (9/25 = 0, 36), then multiply the obtained dividend by 100 (36%). The final number should coincide with the starting percentage coefficient.
Step 3. Delete the percent sign
After the original percentage has been converted to a decimal number or fraction, the% symbol is no longer indicated. Remember that a percentage indicates a part of the total set which is represented by the number 100. So, if you don't remove the% symbol after the conversion, your solution to the problem is incorrect.
Method 2 of 3: Converting the Decimal Numbers
Step 1. To convert a decimal number to a percentage, multiply it by the coefficient 100
In other words, move the decimal point (the comma) two places to the right. The percentage symbol translated into words literally means "percent", so after being multiplied by a hundred, a decimal number becomes a percentage. Here are some examples: 0, 32 expressed as a percentage becomes 32%; 0, 07 expressed as a percentage becomes 7%; 1, 25 expressed as a percentage becomes 125%; 0, 083 expressed as a percentage becomes 8, 3%.
Step 2. Convert a limited decimal number to a fraction
A decimal number is said to be limited when it is made up of a finite number of decimal digits. Shifts the decimal separator, i.e. the comma, to the right by the number of decimal digits present. The number obtained represents the numerator of our fraction. The denominator is represented by the number 1 followed by as many 0s as the decimal places of the original number. As a last step, let's simplify the fraction obtained to a minimum.
- For example: the number 0, 32 has two decimal places, so we move the decimal separator to the right two places and divide the result by 100 to get the fraction 32/100. Having a greatest common factor equal to 4, the fraction resulting from the previous step can be simplified into the form 8/25.
- Here is another example: the number 0, 8 has a single decimal place, so, by moving the decimal point to the right by one position and dividing the result by 10, we will get the following fraction 8/10. Simplifying the result using the greatest common divisor 2 we will get the fraction 4/5.
- To verify the correctness of your work, you simply have to calculate the result of the fraction, making sure that it is identical to the starting decimal number. In our example we get 8/25 = 0, 32.
Step 3. Convert a periodic decimal number to a fraction
A periodic decimal number is a number made up of infinite decimal digits that are repeated regularly. For example, the decimal number 0, 131313… is made up of two digits (1 and 3) that are repeated indefinitely. Determine the number of digits that make up the "period" of the number under consideration (i.e. the decimal digits that repeat endlessly), then multiply the whole number by 10, where "n" represents the number of digits that make up the period.
- For example: 0, 131313 … must be multiplied by 100 (result of 102) thus obtaining 13, 131313….
- To determine the numerator of our fraction it is necessary to subtract the decimal part from the number obtained in the previous step. In our example we will have 13, 131313… - 0, 131313… = 13.
- To determine the denominator, 1 must be subtracted from the power of 10 used in the first step of the conversion. In our example 0, 131313… has been multiplied by 100, so the denominator will be 100 - 1 = 99.
- At the end of the conversion, we can write that the periodic decimal number 0, 131313… in fractional form is expressed as 13/99.
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Here are other examples:
- 0, 333… is represented by the fraction 3/9;
- 0, 123123123… is represented by the fraction 123/999;
- 0, 142857142857… is represented by the fraction 142857/999999.
- If necessary, the fraction resulting from the conversion can be simplified to a minimum. For example, simplifying the fraction 142857/999999 yields 1/7.
Method 3 of 3: Converting the Fractions
Convert Percents, Fractions, and Decimals Step 7 Step 1. To convert a fraction to a decimal number, simply divide the numerator by the denominator
Interpret the fraction symbol as having to perform a division. This means that any fraction of the form "x / y" can be described as "x divided by y".
For example: the fraction 4/8 results in the decimal number 0, 5
Develop a Business Process Step 3 Step 2. Determine how to round the decimal number resulting from the conversion
Many fractions do not result in a whole number, in which case it is therefore necessary to evaluate to which decimal to round the final result of the division. The most frequently adopted convention is to use 2 decimals. Remember the basic rule for rounding a truncated decimal number: if the first truncated number is 5, the previous digit must be rounded to the next higher decimal. For example, the decimal number 0, 145 should be rounded to 0, 15.
- For example: the fraction 5/17 gives as a result the decimal number 0, 2941176470588…;
- The final rounded result will simply be 0.29.
Convert Percents, Fractions, and Decimals Step 9 Step 3. To convert a fraction to a percentage, divide and multiply the result by 100
Let's start by proceeding exactly like converting a fraction to a decimal number, then divide the numerator by the denominator. At this point we multiply the result obtained by 100 and complete the conversion by adding the symbol of%.
- For example, let's convert the fraction 4/8 by dividing 4 by 8, thus obtaining 0, 50. At this point we multiply the result by 100 obtaining the final answer that is 50%.
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Here are other examples:
- 3/10 = 0, 30 * 100 = 30%;
- 5/8 = 0, 625 * 100 = 62, 5%.
Advice
- An excellent knowledge of arithmetic tables (multiplication tables) will be of great help to you.
- Respect the teacher's or professor's opinion about using the calculator in the classroom. If the use of such a tool is not permitted or well regarded, it is best not to use it.
- Many calculators are equipped with the function for calculating fractions. In this case it may be useful to use the calculator to reduce a fraction to its lowest terms. For more details on the procedure to follow, consult the instruction manual of the device.
Warnings
- Make sure that the decimal separator (comma) is entered in the correct position.
- When converting a fraction to a decimal number, be sure to divide the numerator by the denominator.
