#importing modules
import math
from __future__ import division
#Variable declaration
n=4; #number of atoms per unit cell(FCC)
M=63.54; #atomic weight of Cu(gm)
N=6.023*10**23; #avagadro number(per g mole)
d111=2.08; #interplanar spacing(angstrom)
h=1;
k=1;
l=1;
#Calculation
d111=d111*10**-8; #interplanar spacing(m)
a=d111*math.sqrt((h**2)+(k**2)+(l**2));
D=(n*M)/(N*(a**3)); #density of Cu(g/cc)
#Result
print "density of Cu metal is",round(D,3),"g/cc"