2.84 2.85 2.86 2.87 2.88 2.89 2.9=?如何简便算?

问题描述:

2.84 2.85 2.86 2.87 2.88 2.89 2.9=?如何简便算?

2.84 +2.85+ 2.86 +2.87+ 2.88+ 2.89 +2.9
=2.87*7
=20.09