Calculating Simple Percentages

The symbol used to show percent is “%” so 17 percent would be 17%. The “17” is the “part” and the “%” is the whole which means that 17% can also be shown as 17/100.

How to Find the Percentage of Any Given Number:

In math you will often have to find the percentage of a number. For example, if you were to go shopping and you found a new shirt that was 20% off, you would need to know what is the number the 20% is off of. The sales tag on the shirt says $20.00. So now you would need to know how to find what 20% of $20.00 is. To do this you must multiply the number ($20.00) by the percent “20”. However if you multiply 20.00 x 20, you would get the answer: “400.00”. That would not be correct. Why, because we need to multiply $20.00 by 20%, not by “20”.

20% must be converted to a decimal number. We know that 20% also equals 20/100. The “100” (which replaces the % symbol) needs to be used to create a decimal number. To show 20/100 as a decimal, we must move a decimal point over to the left, beginning to the immediate right of the “0” in “20”, two spaces so 20/100 becomes .20. That decimal point is used in place of the “100” and/or the “%”. We can then multiply $20.00 by .20 so: 20.00 x .20 = 4.00. This tells us that 20% of $20.00 is $4.00.

How to Determine the Percentage of Any Given Number:

Now if you are looking to find what the percentage is, let’s say if you took 20 cans of soda from a package of 80, you would need to divide 20 by 80 so it would be written out as: 20 ÷ 80 = .25. Now we must reverse the decimal to a percentage. To do this, we now need to move the decimal point over two spaces to the right so that .25 becomes 25 and the decimal becomes the symbol “%” so the answer would be 25%. This means that 20 cans of soda removed from a package of 80 cans equals 25%.