4.04 Percentages with technology

When inputting decimals into a calculator we use the "." button. Using this button, we can input decimals by pressing this button after the ones digit and before the tenths digit. To input 15.9 into our calculator we press:

To get the calculator to return the answer of 15.9 we should also press the = or the "enter" button.

Depending on the type of calculator, the result of a calculation will be expressed as either a decimal or as a fraction.

To convert from a fraction to a decimal we can use this button.

When converting percentage values into non-percentage values without a calculator, we would remove the \% symbol and then divide by 100. This method doesn't change when using a calculator, we just don't have to evaluate the division by ourselves.

There are also some calculators that have a percentage function which may be stored as an alternative command. On most calculators, this function has the same effect as dividing by 100.

If the calculator's \% function acts as division by 100 then the output of will be the decimal or fraction equivalent to the percentage inputted. We can use this function to convert percentage values into non-percentage values by inputting them into the calculator and evaluating the expression.

It should be noted that the calculator cannot give percentage values as outputs. In our working out we would usually multiply by 100\% to convert a non-percentage value into a percentage value. When using a calculator we need to break this up into two steps:

1. Multiply the non-percentage value by 100

2. Attach the \% symbol to the result when writing the answer

To input 59\% into the calculator, we press:

To get the calculator to return the value we should also press the = or the "enter" button.

If the calculator's \% function acts as division by 100 then the output of this expression will be 0.59 or \dfrac{59}{100}.

Examples