0.78×10.1=0.78x(10+0.1)=0.78x10+0.78x0.1=7.8+0.078=7.878
0.78*10.1=0.78×(10+0.1)=0.78×10+0.78×0.1=7.8+0.078=7.878
0.78×10.1=0.78×(10+0.1)=0.78×10+0.78×0.1=7.8+0.078=7.878
=0.78*10+0.78*0.1=7.8+0.078=7.878