12×50= 40×30= 25×40= 84÷7=
306÷3= 124×2= 102×5= 160÷4=
+ = 1- = - = + =
①7.4﹣6.62+20.6﹣13.38
②×+×
③(-+)÷
④2×0.8×12.5×50%
⑤÷(÷+)
⑥×[1÷(+)]
3.7+5.6= 2.4÷0.08= += 8﹣= 0.23=
×6.4= ×= 3÷1%= 4a+a= 6×÷6×=