Someone suggested another way for me to measure the RMS of a sine wave by
just multiplying the samples by .707 using floating point methods and
accumulate that in just 16 bits.

How does that compare in effectiveness, speed, code size, to doing the other
method of squaring every sample, accumulating 24 bits, then squarerooting?

Whichever method I choose, how does the final answer work out with it having
decimal places?  Again I find myself trying to figure out how to think in
terms of binary....but suppose I took the square root of 255, which is
15.968,
how does that look in the pic and how do I handle it?