Question

[(8.1-5.6)×0.9-1]×0.4简便运算？

Answer 1

[（8.1－5.6）×0.9－1]×0.4
=（2.5×0.9－1）×0.4
=2.25×0.4－1×0.4
=9－0.4
=8.6

Answer 2

[(8.1-5.6)×0.9-1]×0.4
=(2.5×0.9-1)×0.4
=2.5×0.9×0.4-1×0.4
=(2.5×0.4)×0.9-0.4
=1×0.9-0.4
=0.5