1．口算：
0 139972 139980 139986 139990 139996 139998 140002 140008 140010 140016 140022 140026 140028 140032 140038 140040 140046 140050 140052 140056 140058 140062 140064 140066 140067 140068 140070 140071 140072 140074 140076 140080 140082 140086 140088 140092 140098 140100 140106 140110 140112 140116 140122 140128 140130 140136 140140 140142 140148 140152 140158 140166 199269
| 3.2：1.6= | 5：2.5= | 4.2÷$\frac{1}{5}$= | 5×$\frac{1}{5}$×0= |
| 10-0.09= | 0.32= | $\frac{1}{5}$×4÷$\frac{1}{5}$×4= | $\frac{2}{9}$+$\frac{7}{9}$×$\frac{3}{14}$= |