Question

简便运算：4.5*9.9*0.45

Answer 1

4.5×9.9×0.45

=4.5×（10-0.1）×0.45

=4.5×10×0.45-4.5×0.1×0.45

=4.5²-0.45²

=（4.5+0.45）（4.5-0.45）

=4.95×4.05

=（5-0.05）（4+0.05）

=20-0.2+0.25-0.0025

=20.0475