7.683×190－768.3×0.8－76.83
=76.83×19－76.83×8－76.83
=76.83×(19-8-1)
=76.83×10
=768.3
1999又9分之8＋2000又9分之8＋2001又9分之8＋9分之4
=2000-1/9+2001-1/9+2002-1/9+4/9
=6003-3/9+4/9
=6003又1/9
1又2/3×1又2/5×1又2/7×1又2/9×1又2/11×.×1又2/199
=5/3×7/5×...×199/197×201/199
=201/3
=67