Unitary Method: (Find 1%)
What is 7% of 78?
To find 1 %, divide 78 by 100 or move the decimal point two places to the left.
1% = 78 / 100 = 0.78
0.78 x 7 = 5.46
5 Basic Percentages Method
Think of percentage closest to 50% (half), 25% (quarter), 10% (one tenth), 5% (one half of 10 percent) and 1% as 100th.
What is 20% of 320?
Since 10% of 320 is 32, hence 20% will be 32+32=64.
What is 67% of 1143?
50% of 1143 is 571.5. 10% = 114.3. 5% = 57.15. 1% is 11.43
571.5+114.3+57.15+11.43 = 765.81
Simple Formulas
What is the percent change from 20 to 50?
Formula: [(New Number – Original Number) / Original Number] x 100
[(60-20) / 20] x 100 = 200%
What percentage is 20 of 40?
Formula: (New Number / Original Number) x 100
(20 / 40) x 100 = 50%
What is 10% of 25?
Formula: (percentage / 100) x Original Number
(10 / 100) x 25 = 2.5
Using Calculator
Example 1: 10% of 25 = 25 x 10% = 2.5
Example 2: add 10% in 25 = 25 + 10% = 27.5
Example 3: discount 10% in 25 = 25 – 10% = 22.5
In Example 1, do NOT press (=) after pressing (%) button. For all others, you MUST press (=) after (%) to get accurate result.
Microsoft Excel Formula To Calculate A Total With Price and Tax
Let’s assume a table with prices and taxes like this;
Price Tax Total
$199.99 12.5% =E10+(E10*G10)
Where data in the cell E10 is Price and G10 is tax rate. Hence, in the total column, you will enter this Excel formula;
=E10+(E10*G10)
Price Tax Total
$199.99 12.5% 224.99
Notes 