99.5+99.6+99.7+82.1+82.2+82.3
=(99.6-0.1)+99.6+(99.6+0.1)+(82.1-0.1)+82.2+(82.2+0.1)
=99.6×3+82.2×3
=3×(99.6+82.2)
=3×181.8
=545.4