怎樣簡便就怎樣算是遞等式計算哦! 8.73+9.99 = =

怎樣簡便就怎樣算是遞等式計算哦! 8.73+9.99 = =

8.73+9.99
=8.73+(10-0.01)
=8.73+10-0.01
=18.73-0.01
=18.72
看不明白要追問喲.