Calculator
  A functional numeric calculator. This uses the numbers at top for the calculations in a sequential order. You can enter numbers by pressing the keyboard equivalents, the numeric keypad number keys (if you have a numeric keypad), or by clicking the buttons for each number directly on the screen. You will only be allowed to enter one decimal point. The numbers are displayed in decimal notation, not scientific notation. The number of decimal places is variable depending upon the numbers entered. To record any displayed result (in the Results Log window), simply click the "Record Display" button at the bottom.
  To perform a calculation, enter the first number, click a function key, and the number displayed will be altered if this is appropriate (eg by clicking the √ key), and then enter the next number and press either "enter" or the "=" key to perform the operation (eg +, -, X, ÷ or any operation with an "r" constant in its name). Consecutive operations can be performed with the displayed number being used in the appropriate position within the operation.
  The operations with an "r" in their name will require at least 2 operands. Several operations will only work with integers, ie x! or factorials, nCr (number of combinations possible) and nPr (number of permutations possible). These will only work with integers, with an error if real numbers are used as operands. They have specific overflow limits as well which will be indicated in the display.
  MR, CM, M+ refer to the memory display which will store one number when M+ is clicked, clears the memory (CM) or recalls the number in memory (RM) respectively.
  C will clear the display.
  The circular trigonometric functions will regard the displayed number as being in degrees or radians depending upon what the pop-up button at the bottom left of the calculator displays.
  The calculator can be left behind other windows on the desktop until needed, and reactivated by clicking on it or selecting its name in the menus.