speed Calculations

[richard]

one of the first rules in mathematical calculations is that 2000/2.xx is accurate to 0 decimal points
2000.0 / 2.xx is accurate to 1 decimal point. to be accurate to 2 decimals all!! input figures must be measured to two decimals , otherwise its fantasy

[richard]

actually its worse than I made out
see this
http://courses.chem.indiana.edu/s117...on-SigFigs.pdf