Question

9.9乘9.9乘0.99 简便计算

Answer 1

9.9乘9.9加0.99
=99×0.1×99×0.1+99×0.01
=99×99×0.01+99×0.01
=（99×99+99）×0.01
=99×100×0.01
=99

Answer 2

9.9乘9.9乘0.99
=(10-0.1)(10-0.1)(1-0.01)
=(10-0.1)(10-0.1)(10-.01)÷10
=（100-1）ˇ3÷10000
=（10ˇ2-1ˇ2）ˇ3÷10000
=[(10+1)(10-1)]ˇ3÷10000
=90ˇ3÷10000
=7.29

追问

呵呵，晕了

追答

上面算错了一点，其实你可以直接用公式的（a-b）ˇ3=aˇ3-3aˇ2b+3abˇ2-bˇ3直接代入计算

追问

我弄错了，是9.9乘9.9加0.99怎样简便？

追答

9.9乘9.9加0.99
=(10-0.1)(10-0.1)+(10-0.1)×0.1
=（10-0.1）（10-0.1+0.1）
=9.9

Answer 3

9.9*9.9 + 0.99
= (10-0.1)^2 + 0.99
= 100 -2 + 0.01 + 0.99
= 100 -2 +1
=99