巧算下面2题99999*2222-3333*66666=（1-1/2）(1/3-1)(1-1/4)(1/5-1)...(

1, 99999*2222-3333*66666=9*2*11111*1111-3*6*11111*1111=0
2, （1-1/2）(1/3-1)(1-1/4)(1/5-1)...(1/2003-1)(1-1/2004)
= (1/2）(-2/3)(3/4)(-4/5)...(-2002/2003)(2003/2004)
= -1/2004