3.99+0.1= 1÷1%= ÷3= 6- = 0.25× ×4=
5-3.09= = 4.3+3.57= 1.9-2÷4= 4× ÷4× =
×= 0×= ÷= +=
□○□=□(颗)
□○□=□(个)
47+53= 420÷70= 100-28.5= 0.03×8= 234- 199=
50×80= 2.7÷0.9= = 1÷ =