Improbability diminishes with accumulation. If we had to worry about the location and vector of each and every electron in the oxygen we breathed or in the iron we used we would die of dither, but as brother particles are added to the first, the certainty increases.  By the time you have a gold wedding ring of 15 grams and 4.6 x 10²² atoms then where the last few of the 3.6 x 10²⁴ electrons fit in is practicably certain.

http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/nucuni.html