1-8分之5/28分之25-40分之3怎樣簡算

1-8分之5/28分之25-40分之3怎樣簡算


1-8分之5/28分之25-40分之3
=1-5/8×28/25-3/40
=1-(28/40+3/40)
=1-31/40
=9/40



1994.4×3.6+2006.9×6.4簡算


=1994.4X(3.6+6.4)+(2006.9-1994.4)X6.4
=1994.4X10+12.5X6.4
=19944+12.5X8X0.8
=19944+100X0.8
=19944+80
=20024



9.6*3.6+7.2*02簡算


是0.2吧?
3.6*(9.6+2*0.2)
=3.6*10
=36