TickCalc
This provides most of the numeric functions I need. I have not included financial functions, but can do this if there is enough interest (sic). This uses the numbers at top for the calculations, which are performed sequentially. You can enter numbers by pressing the keyboard number keys, the numeric keypad number keys (if you have a numeric keypad), or by clicking the buttons for each number directly on the screen with the mouse (though this is painfully slow).
There are sufficient controls to ensure only valid numbers are entered, eg you will only be able to enter one decimal point. The numbers are displayed in decimal notation only, ie not scientific notation (eg 1.2E10). The number of decimal places for display of the results can set by the popup menu at the bottom. The left bottom popup menu determines whether circular functions use degrees or radians. I use extended reals in all non-integer calculations (10 bytes) so can claim accuracy to 17 or so significant figures.

Operation
•To perform a calculation, enter a number, and click a function key (eg the √x  key). If an answer can be computed instantly, then the display will be updated. If another number is required (eg with the +, -, X, ÷ or any operation with an "r" constant in its name) enter the next number, then press either "enter" or the "=" key to perform the operation.
•Consecutive operations can be performed with the displayed number used consecutively in the subsequent operation.
•To reiterate, the operations with an "r" in their name will require at least 2 operands before a result can be calculated.
•Several operations will only work with integers, eg x! (factorials), nCr (number of combinations possible) and nPr (number of permutations possible), with an error if real numbers are used as operands. There are limits to the numbers which can be used in these calculations, and if you overdo it, the display will inform you that you have overflowed.
•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 (MR) respectively.
•C will clear the display.
•π and e can be activated from the keyboard by pressing the "p" or "e" keys respectively.
•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 menu.