I recently bought a digital scale that doesn't include a calibration weight. I got this scale because of the big easy to read display. The instructions call for a 200 gram weight to calibrate. Of course I looked on line and found weights available but the prices are high. The scale has a resolution of 0.01 grams which equals 0.154 grains. I suppose my question is about the tolerance of error. I'm considering ASTM 4 or OIML F2. Am I thinking this right?