3.6*99+3.6
=3.6*99+3.6*1
=3.6*(99+1)
=3.6*100
=360
2.8*99+28*0.1
=2.8*99+2.8*1
=2.8*(99+1)
=2.8*100
=280
78*101-78
=78*101-78*1
=78*(101-1)
=78*100
=7800
0.87*8.7*99
应该是不是“0.87*10+8.7*99”呀
0.87*10+8.7*99
=8.7*1+8,7*99
=8.7*(1+99)
=8.7*100
=8700