[FotoPlasma]

(1/4in)/2 = 1/8in
pi(1/8in)^2 = 0.049087385212341in^2
0.049087385212341in^2 * .125in = 0.0061359231515426in^3
1/0.0061359231515426in^3 = 162.9746617261 quarter inch holes per in^3
(I love my TI-89)
solve(((162.9746617261holes)/(0.098lb/in^3))=((x)/(1)),x)
According to my calculations, 1663.0067523071 holes per lb of aluminum...

If any of that looks wrong, please alert me to it immediately...

I hope that's right... it's kinda late...