My chicks are 4 wks old and I was thinking about chick days (got them from TSC) then I saw some posts about chicken math, then I realized that chicken math set in from day one! My TSC sells out in an hr so I went early that morning and made sure I was first in line. First they only got in red pullets, and although we had only wanted two red pullets we figured since we were planning on getting 8 pullets all together just go ahead and get 8 red pullets. Well then as we were checking out they got a call that 4 other boxes of chicks had arrived, so we waited. Then the chicks and ducks came in and we ended up with 6 more pullets and 2 ducks! So 8+6+2= 14! not 8. Chicken math!