The Windows Calculator can be operated in several modes, one of which is the Programmer mode. To use Windows Calculator to convert Decimal to Binary, you have to use the Programmer mode.

You can use the Sum function in Microsoft Office... Excel will only produce binary numbers with up to 10 bits. This means that it can only convert decimal numbers greater than -513 and less than 512.

but by using the leading zero, I also indicated that I was specifying a value in octal too. Ergo, 0500 = 500. That's nice, but no binary, which is a definite limitation. But, I'm not done yet. There's ...