That math doesn’t quite work out. Even if we assumed he had no hairs to begin with (which he does), at 1 hair a week it would take 9 years and 32 weeks to grow 500 hairs. By that time, all but the last 32 hairs or so would already be 1/2" long. It would then take 4 months for the last hairs to catch up (or for all the hairs to grow to 1/2", if he shaved), which makes a total of about 10 years (+/- a few weeks due to rounding).
May 24, 2016