问题 解答题 口算56+289=1.9+2.09=13+14=0.3-0.03=9+99+999+3=35×57=0.01÷0.2=56×310=12-13=7.2÷9= 答案 56+289=3451.9+2.09=3.9913+14=7120.3-0.03=0.279+99+999+3=111035×57=250.01÷0.2=0.0556×310=1412-13=167.2÷9=0.8