7．口算．
0 154775 154783 154789 154793 154799 154801 154805 154811 154813 154819 154825 154829 154831 154835 154841 154843 154849 154853 154855 154859 154861 154865 154867 154869 154870 154871 154873 154874 154875 154877 154879 154883 154885 154889 154891 154895 154901 154903 154909 154913 154915 154919 154925 154931 154933 154939 154943 154945 154951 154955 154961 154969 199269
| 0.1÷0.01= | 5×24%= | 0.125×（8+80）= |
| 2.5×1.7×0.4= | 1-$\frac{2}{5}$+$\frac{3}{5}$= | （$\frac{5}{7}$-$\frac{1}{6}$）×42= |