The Calculation of Percentage or how to find Percent
� Percentage means "per hundred"�signifying�that the percent amount is given for each 100 units. Thus 10% of 100 would be 10 or 10 parts out of the 100.�Whenever�the�terms, "for each" or "of", are used in a math problem it means multiplication is called for, so when trying to find 25% of 64, it means multiplication will be used. First change the percentage into a decimal, meaning a number with a decimal point and without a percent symbol.�To do that, first�understand any number written without a decimal is accepted as having a decimal to the right of the digit on the far�right. Thus the number 8 is also 8.0, and 25 is 25.0 with the zero to the right of the decimal point not having any value and so not changing the number's value.
To change a percent to a decimal move the decimal point two places over to the left. This means that 25% becomes .25 as a decimal, because as stated when 25 is�written without a decimal, one is understood to be on the right of the�5 and moving it two places to the left puts it to the left of the�2 . Sometimes percents are written with decimals, such as 3.35%�which also is�without two digits�to the left side of the decimal. In this case it is understood that there are zero's to the left of the given digits and by simply placing enough 0's�on the left side�the decimal can be moved over two places. So 3.35% becomes .0335 as a decimal�and .09% would be .0009 when the decimal point is moved over two places to the left.
After�changing�the percent to a decimal simply do the multiplication and place�a decimal in the correct place in�the answer. For 25% of 64, mulitply .25 times 64 to get 1600 and then because the number .25�has two digits to the right of a decimal, the understood decimal at the right side of 1600, must be moved two places to the left to get 16.00 as�an answer. So 25% of 64 equals 16.
The�total number of�digits that are to the right of decimals in the numbers to be�multiplied together determines�the total number of places the decimal is moved to the left in the answer. Thus 3.35% of 15.7 becomes, .0335 times 15.7 ( only the percent has to have the decimal moved). When multiplied together they give, 52595, but then the decimal has to be moved�over five places to the left to get, .52595��as the correct answer. The decimal is moved five places because .0335 has four digits right of the decimal and 15.7 has one digit right of the decimal, so totally they have five digits to the�right of�decimals.
Another way to think about percentages is in terms of fractions. A percent refers to parts out of 100 so it is equal to a fraction where the percent amount is the numerator and 100 is the denomenator. So 14% is equal to 14/100 and 6.25% equals 6.25/100. Notice the decimal is not moved when writing 6.25% as a fraction. Knowing this will help�to understand why�25% equals 1/4 , 50% equals 1/2 , 33% equals appox. 1/3, and 75% equals 3/4. These fractional parts are fairly easy to figure�and remember in one's�head. By knowing what percentages these simple fractions�are equal to it is easier to find percentages involving them. For example, one half of 360 is 180, so 50% of 360 is 180, one third of 30 is 10 so 33% of 30 is approx. 10, and one fourth of 12 is 3 so 25% of 12 is 3. Instead of changing the percent to a decimal, it can be changed to a fraction and then multiplied be to find the percentage of a number. As an example to find 14% of 50, change 14% to 14/100 which reduces to 7/50. Multiply 50 time 7/50 to get 350/50.�To change 350/50 to a whole number,�350 is divided by 50 to get�the number 7, so 14% of 50 equals 7.
In short, to find a percentage, change the percent to a decimal, multiply the amounts together, and put the decimal in the correct place in�the answer or change the percentage to a fraction and multiply by it.�Use percentage math to�figure out interest on credit cards, yield on savings accounts, sale amounts on percent off sales, and fees that are given as a percent of the total. Just remember that with yields on savings, and cds, and charges on loans and morgages,�time is a factor also. How often the interest is compounded has to be figured in when adding up the percentages. Often when computing percentages of money amounts answers must be rounded to the nearest cent. Take 39% of 7.35, 39% is equal to .39, which when multiplied by 417.35 gives an answer of 162.7665 and since dollar amounts are given�to the nearest cent the answer is rounded to 2.77.
When figuring percent discount and percent off sales a good calculator will come in handy only if the math is understood. For example if a sale�item has 15% off the regular price of .95, to find the sales price�the percentage amount must be found and then that amount is taken off�of the regular price. 15% is equal to .15 which multiplied by 3.95 gives .5925. Rounded to the nearest cent .5925 is equal to .59 cents. This is the amount of the discount so subtracting it from the regular price of .95 gives .36 for the sales price.�
Written by aufan
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