I had a DUH! moment this morning. For a couple of years now I have been figuring cross sectional area using pi and algebraic formulas. For the last month I have been trying to teach these formulas and methods to people that hardly read and write.
I sat down this morning and reduced the equations to one simple method:
For round to square: Diameter x 0.885 = length of sides of the square.
For square to round: length of side of square / 0.885 = diameter.