99.9×99.9怎么巧算?
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/04 14:29:12
![99.9×99.9怎么巧算?](/uploads/image/z/1649501-53-1.jpg?t=99.9%C3%9799.9%E6%80%8E%E4%B9%88%E5%B7%A7%E7%AE%97%3F)
99.9×99.9怎么巧算?
99.9×99.9怎么巧算?
99.9×99.9怎么巧算?
99.9×99.9=(100-0.1)^2=100^2-0.1^2=10000-0.01=9999.99
(100-0.1)^2
99.9×99.9
=(100-0.1)×(100-0.1)
=100×100-2×100×0.1+0.1×01.
=10000-20+0.01
=9980+0.01
=9980.01