3.3✖️6.6➕9.9✖️7.8的简便方法？

Question

如题所述

Answer 1

3.3×6.6+9.9×7.8
＝3.3×3×2.2+9.9×7.8
＝9.9×2.2+9.9×7.8
＝9.9×(2.2+7.8)
＝9.9×10
＝99