3.2×12.5×25 5.6×1.7＋0.56×83 4821－998 102×0.87 25分之7×103－25分之7×2－25分之7 简算

3.2×12.5×25
=0.8×4×12.5×25
=0.8×12.5×(4×25)
=10×100
=1000
5.6×1.7＋0.56×83
=0.56×17+0.56×83
=0.56×(17+83)
=0.56×100
=56
4821－998
=4821-1000+2
=3821+2
=3823
102×0.87
=(100+2)×0.87
=87+1.74
=88.74
25分之7×103－25分之7×2－25分之7
=7/25×(103-2-1)
=7/25×100
=28