口算．
1.8×0.5=            49×0.2=             10÷2.5=           0.83÷0.1=          2.4﹣0.8=
0.44÷2.2=           0.6×0.5=            0.4+0.15=          1.25×8=            0.56÷8=
12.5×18.5×0.8=     5.38+0.45+1.55=      0.42÷0.7÷0.6=    0.74×0.6+0.74×0.4=