37*9.9=37*(10-0.1)=37*10-37*0.1=370-3.7=366.3
37*9.9=111*3.3=(100+10+1)*3.3=330+33+3.3=366.3
=37X(10一0.1)=37X10一37X0.1=370一3.7=366.3