The coefficient of x9 in the expansion of (1 + x) (1 + x2) (1 + x3) ... (1 + x100) is _______.

x9 can be formed in following eight ways.i.e., x9,x1+8,x2+7,x3+6,x4+5,x1+2+6,x1+3+5,x2+3+4and coefficient in each case is 1.∴ Coefficient of x9 = 1 + 1 + 1 +... 8 times                                = 8