直接写得数．
56+2.4=　      1﹣0.48=　      0.81÷3=　   　
0.5×2.4=　     4×0.24+0.24=　     5﹣5=　   　
3.2÷0.4=　     0.05×20=　      8.2÷0.01=　   　
6.8﹣1.3﹣2.7=　   　．