16．口算
0 159714 159722 159728 159732 159738 159740 159744 159750 159752 159758 159764 159768 159770 159774 159780 159782 159788 159792 159794 159798 159800 159804 159806 159808 159809 159810 159812 159813 159814 159816 159818 159822 159824 159828 159830 159834 159840 159842 159848 159852 159854 159858 159864 159870 159872 159878 159882 159884 159890 159894 159900 159908 199269
| 45+55= | 3000-1800= | 4500+2500= | 324×2= |
| 200-178= | 700×6= | 59÷9= | 78×0= |
| 1-$\frac{3}{5}$= | $\frac{3}{5}$+$\frac{2}{5}$= | 901×8≈ | 989+605≈ |