(9991*1999.1999+9991.9991*1999)/2.0002 尽量简算

问题描述:

(9991*1999.1999+9991.9991*1999)/2.0002 尽量简算

= 9991(1999.1999+1.0001*1999)/2.0002
= 9991*1999(1.0001+1.0001)/2.0002
= 9991*1999
= (10000 - 9)(2000 - 1)
= 20000000 - 10000 - 18000 +9
=19972009