(6584×101－6584)
=6584(101-1)
=6584×100
=658400
(2)(21／20－14／3＋42／5)×42
=(1+1/20+8+2/5)×42-14/3×42
=(9+9/20)×42-196
=378+23+2/5-196
=205又2/5