Percentages can add another layer of complexity to mathematical equations. Combined with ordinal figures, subtraction of a percentage often requires patience and time to work out. While mental arithmetic is a useful skill to develop, sometimes speed is of the essence. Fortunately, subtracting a percentage from an ordinal number on a calculator is a straightforward operation.

- Skill level:
- Easy

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### Things you need

- Calculator

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## Instructions

- 1
Turn on your calculator. Have the figure you wish to subtract 20 percent from at hand. You may need to add several figures together to get a total from which to take away the percentage. This would be the case if you wish to subtract 20 percent from a select number of figures on a numerical list.

- 2
Enter the figure from which you want to subtract 20 percent. In this example, use 150.

- 3
Press the multiplication button on the calculator. It is symbolised by an “X.”

- 4
Enter “0.8. This figure represents 80 percent (it is 80 percent of “1”). If you multiply a number by 80 percent, you are automatically subtracting 20 percent from it. In the example used, the equation would read “150 x 0.8.”

- 5
Press the equals button, symbolised with the sign “=.” This will give you the result. In the above example the result is 120. You have subtracted 20 percent of 150.

#### Tips and warnings

- It is always a good idea to repeat the calculation to double-check your answer, particularly if the equation is for a test or to calculate a payment.