2.6×9.9=2.6×（10-0.1）=26-0.26=25.74
2.6 X (10-0.1)=2.6 X 10-2.6 X 0.1=26-0.26=25.74 希望能帮到你！
=2.6×(10-0.1)=2.6×10-2.6×0.1=26-2.6=23.4
2.6*10-2.6*0.1
