It is Avogadro's number - the number of atoms of a substance in a mole (measurement, not animal) of that substance ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Mary Gasch, Mathematics Instructor Nerinx Hall, Webster Groves, Missouri http://65.66.41.6/~3gasmar/mgasch.html AOL IM: Mrs G Math Teacher ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ On May 10, 2011, at 7:54 AM, Sarah Chisholm wrote: > (6.02 x 10²³)