clc 
// Given that
w = 207.2 // atomic weight of Pb
d = 11.36e3 // density of Pb in kg/m^3
a = 3.2e-10 // length of cube edge in meter
N = 6.023e26 // Avogadro's no. in per kg mole
// Sample Problem 11 on page no. 13.28
printf("\n # PROBLEM 11 # \n")
printf("Standard formula used \n")
printf(" n = (a^3 * d * N) / w \n")
n = (a^3 * d * N) / w
printf("\n Number  of atom per unit cell is %d.",n)