3.9+39.9+399.9+3999.9用简便算法
问题描述:
3.9+39.9+399.9+3999.9用简便算法
答
3.9+39.9+399.9+3999.9
=(4-0.1)+(40-0.1)+(400-0.1)+(4000-0.1)
=(4+40+400+4000)-(0.1+0.1+0.1+0.1)
=4444-0.4
=4443.6