下面各题怎样简便就怎样算．
4.23+3.6﹣0.23+6.4          5.12+5.12×99                  8.5×6÷8.5×6
18÷0.45                     50.8÷（26.5﹣7.5×3）        1.8÷[0.216÷（0.7﹣0.46）]．