甲数除以乙数(不为0)等于甲数乘乙数的倒数．

37+58=      810-540=       19×40=      910÷70=      68-0.8=

4÷24=      8.2÷0.1=    12×25%=     + ＝       803-204≈

  × =     ÷ =      4.48+5.52=    2.02-1.43=    0.08×0.25=

15.9÷3=     1- ＝       - =        0.2 ²=       3.2÷0.01=

20×30                           0.2×0.3                            

=(2×10)×(3×10)      =(2×0.1)×(3×0.1)

=(2×3)×(10×10)     =(2×3)×(0.1×0.1)

=6×100                 =6×0.01

=600                     =0.06