Secrets using Calculator in Windows 

You can use Calculator to perform simple calculations such as addition, subtraction, multiplication, and division. Calculator also offers the advanced capabilities of a programming, scientific, and statistical calculator.

You can perform calculations by clicking the calculator buttons, or you can type calculations by using your keyboard. You can also use the numeric keypad to type numbers and operators by pressing Num Lock. For more information about using the keyboard with Calculator, see Keyboard shortcuts.

Calculator window

1. I’m pretty sure everyone does this, but a quick way to open it is: 
2. Windows Key –> R –> Calc –> Enter
3. Click the View menu, and then click the mode that you want.
4. When you switch modes, the current calculation is cleared. Calculation history and numbers stored by the memory keys are retained.
5. Click the calculator keys to perform the calculation you want.

 Using Scientific mode

1. Click the View menu, and then click Scientific.
2. Click the calculator keys to perform the calculation you want.
   To access inverse functions, click the Inv key.

   Notes

   • In Scientific mode, Calculator is precise to 32 significant digits.

   • Calculator honors operator precedence when calculating in Scientific mode.

 Using Programmer mode

1. Click the View menu, and then click Programmer.
2. Click the calculator keys to perform the calculation you want.

   Notes

   • In Programmer mode, Calculator is precise up to 64 bits, depending on the word size that you've selected.

   • Calculator honors operator precedence when calculating in Programmer mode.

   • Programmer mode is an integer only mode. Decimal portions are discarded.

 Using Statistics mode

When you use Statistics mode, you can enter the data that you want to calculate statistics for and then perform the calculations. When you enter the data, it's displayed in the history area and the number of values you have entered is displayed in the calculation area.
1. Click the View menu, and then click Statistics.
2. Type or click your first piece of data, and then click Add to add the data to the dataset.
3. Click the button for the statistical calculation you want to perform:

   Button	Function
   	Average of the values
   	Average of the square of the values
   	Sum of the values
   	Sum of the square of the values
   	Standard deviation
   	Standard deviation of population

 Using calculation history

Calculation history keeps track of all the calculations that Calculator performs in a session and is available in Standard and Scientific modes. You can change the values in the calculations in your history. While you're editing the calculation history, the result of the selected calculation is displayed in the result area.
1. Click the View menu, and then click History.
2. Double-click the calculation that you want to edit.
3. Enter the new values that you want to calculate, and then press Enter.

Note
Calculation history is kept separately for Standard and Scientific modes. The history that's displayed depends on the mode that you're using. 

Convert values from one unit of measurement to another

You can use Calculator to perform conversions for different units of measure.
1. Click the View menu, and then click Unit conversion.
2. Under Select the type of unit you want to convert, click the three lists to select the types of units you want to convert, and then, in the From box, enter the value that you want to convert.

 Calculate dates

You can use Calculator to calculate the difference between two dates or to add or subtract days from a specified date.
1. Click the View menu, and then click Date calculation.
2. Under Select the date calculation you want, click the list and select the type of calculation that you want to perform.
3. Enter the information, and then click Calculate.

 Calculate fuel economy, lease, or mortgage payments

You can use the Fuel economy, Vehicle lease, and Mortgage worksheets in Calculator to calculate your fuel economy, lease payments, and mortgage payments.
1. Click the View menu, point to Worksheets, and then click the worksheet for the calculation you want.
2. Under Select the value you want to calculate, click the variable that you want to calculate.
3. Enter the known values in the text boxes and then click Calculate.