2.5除5=0.5
1.5除3=0.5
6.3除7=0.9
6.4除8=0.8
1.6除4=0.4
8.1除9=0.9
4.6除2=2.3
3.6除3=1.2
12.8除2=6.4
12.6除3=4.2