Percentages are used everywhere. For example, you have to make a down payment based on a percentage of the starting amount; your construction mortgage draws are split up and paid in draws based on percentages.
If you are building a home, guaranteed you would run into something expressed in a percent value. The slope of a garage slab, a deck slope, the laying of septic field pipes, etc., you will have to make the basic calculations using percentages!
Or, if all fails, you can use one of
these calculators.
Calculating a percentage of an amount
The easiest way of calculating a percentage of an amount for me is to divide the amount by 100 to get the 1% value and then multiply that with the percentage amount.
starting amount = 240 ( 100%)
percentage = 12%
divide 240 to 100 to get the 1% value
240 ÷ 100 = 2.40
one percent of 240 = 2.4
calculate what 12% is by multiplying the one percent amount of 2.4 by 12;
2.4 * 12 = 28.8
12% of 240 equals 28.8
As a fraction of an amount
Make it even more confusing. At times you have to subtract an amount expressed as a fraction.
starting amount = 240
fraction = 3/25
covert the fraction to a decimal by dividing the numerator 3 by the denominator of 4;
12 ÷ 100 = 0.12 (if you multiply 0.12 by 100 you get the percent value; 0.12 * 100 = 12%)
multiply the starting amount of 240 by decimal 0.12
240 * 0.12 = 28.8
3/25 of 240 equals 28.8
Percentage of an amount by converting the percentage to a decimal
A much simpler way of doing a calculation using percent values.
Starting amount = 240 = 100%
Percentage = 12%
Convert the 12% to a decimal number by dividing it by 100
12 ÷ 100 = 0.12
12% in a decimal is 0.12
multiply the starting amount of 240 by decimal 0.12;
240 * 0,12= 28.8
and again 12% of 240 = 28.8
This final way of calculating the percent value is the best way to get use to working with percentages.
Calculating a Discount Percentage
With a discount in a percentage, the percentage discount reduces the starting amount. If the starting amount is equal to 100%, and the discount is 24%, then the final amount you pay is 100% - 24% = 76% of the starting amount.
Example calculation;
starting amount = $369.55
discount = 11%
If $369.55, the starting amount is equal to 100% after applying the 11% discount, the new price will be 100% - 11% = 89% of the starting amount.
Convert 89% to a decimal number by dividing 89 by 100;
89 ÷ 100 = 0.89
89% in a decimal is 0.89
multiply the starting amount of $369.55 by the decimal0.89;
369.55 * 0.89 = 328.8995 rounded to 328.90
The starting amount of $369.55 after applying an 11% discount is $328.90
11% of $369.55
If all you need to know what 11% is in a dollar value, first convert the 11% to a decimal by dividing it by 100;
11 ÷ 100 = 0.11
11% in a decimal is 0.11
multiply $369.55 by decimal 0.11 ;
369.55 * 0.11 = 40.6505 rounded to 40.65
11% of $369.55 is $40.65
Alternate Way
An alternate way which some of us find easier to do;
divide the $369.55 by 100 and multiply the result by 11;
369.55 ÷ 100 = 3.6955 * 11 = 40.6505 rounded to 40.65
The discount equals $40.65.
Calculating a Surcharge Percentage
A surcharge percent is a percentage added to a starting amount, which means that the amount increases. If the starting amount equals 100% and the surcharge is 30%, then the final amount will equal 130% of the starting amount. Done much the same way as with a discount, but instead of reducing, it increases the starting amount.
Example calculation;
starting amount = $1200.00
surcharge = 30%
if $1200.00 is the starting amount, and equal to 100% after applying the 30% surcharge, the new price will be 130% of $1200.00.
convert the 130% to a decimal number by dividing 130 by 100;
130 ÷ 100 = 1.3
130% in decimal is 1.3
multiply the starting amount of $1200.00 by the decimal 1.3 to get the final amount;
1200.00 * 1.3 = 1560
The starting amount of $1200.00, with a 30% surcharge, is $1560.00
30% of $1200.00
If all you need to know what 30% is in a dollar value, first convert the 30% to a decimal by dividing it by 100;
30 ÷ 100 = 0.3
30% in a decimal is 0.3
multiply $1200.00 by decimal 0.3
1200 * 0.3 = 360
30% of $1200 is $360
Alternate Way
Again an alternate way which some of us find easier to do;
divide the $1200 by 100 and multiply the result by 30;
1200 ÷ 100 = 12 * 30 = 360
The surcharge amount is $360.00