99.9×10.1+99.9×99
=99.9×(10+0.1)+99.9×(100-1)
=999+9.99+9990-99.9
=1000-1+10-0.01+10000-10-100+0.1
=10000+(1000-100)-1+(0.1-0.01)
=10899+0.09
=10899.09
原式=99.9*109.1
=[(99.9+0.1)-0.1]*109.1
=(100-0.1)*109.1
通过加减0.1 使99.9凑出100,化简计算。
方法1:
99.9x10.1+99.9x99
=99.9x(10.1+99.9)x99
=(100-0.1)x(100-1)+99.9
=10000-100-10+0.1+99.9
=10000-10
=9990
方法2:
99.9x10.1+99.9x99
=(100-0.1)x99+99.9
=9900+99.9-9.9
=9900+90
=9990
两种方法😃😃
99.9×10.1+99.9×99
=(100-0.1)×(99+10.1)
=100×109.1-0.1×109.1
=10910-10.91
=10910-10-0.91
=10900-0.91
=10899.09
抄错题了吧,99应该是9.9
99.9×(10.1+9.9)
=99.9×20
=(100-0.1)×20
=2000-2
=1998