1999×0.99×0.9=?(简算)
问题描述:
1999×0.99×0.9=?(简算)
答
1999×0.99×0.9
=(2000-1)×(1-0.01)×(1-0.1)
=(2000-1-20+0.01)×(1-0.1)
=1979.01×(1-0.1)
=1979.01-197.901
=1781.109