12．口算题．
0 159755 159763 159769 159773 159779 159781 159785 159791 159793 159799 159805 159809 159811 159815 159821 159823 159829 159833 159835 159839 159841 159845 159847 159849 159850 159851 159853 159854 159855 159857 159859 159863 159865 159869 159871 159875 159881 159883 159889 159893 159895 159899 159905 159911 159913 159919 159923 159925 159931 159935 159941 159949 199269
| 380÷19= | 40×100= | 2020÷20= | 75-75÷5= | 40+360÷90= |
| 15×4×8= | 100-13×6= | 660÷60= | 70×30= | 34÷17×20= |