Then, now that I knew that there are about 406 millimeters in a strand, I simply divided that by the width of my beads (4mm). 406 / 4 = about 100, and sure enough (I only counted one strand!) I had about 98 beads on that strand (I think I lost count a couple times). Most bead factories simply string the beads on by the length of the strand, rather than counting, so I've found that for smaller size beads, the bead count is within a few beads, give or take, of my mathematical calculation, which is close enough for me.