A = (1 - 1/2) x (1 - 1/3) x (1 - 1/4) x (1 - 1/5) x ... x (1 - 1/2003) x (1 - 1/2004)

A= ( 1 - 1/2 ) x ( 1- 1/3 ) x ( 1- 1/4 ) x ( 1- 1/5 ) x ... x ( 1- 1/ 2003 ) x ( 1- 1/ 2004 )
a) 254 x 399 - 145 / 254 x 399 x 253
b) 5932 + 6001 x 5931 / 5932 x 6001 - 69