18．计算
0 160923 160931 160937 160941 160947 160949 160953 160959 160961 160967 160973 160977 160979 160983 160989 160991 160997 161001 161003 161007 161009 161013 161015 161017 161018 161019 161021 161022 161023 161025 161027 161031 161033 161037 161039 161043 161049 161051 161057 161061 161063 161067 161073 161079 161081 161087 161091 161093 161099 161103 161109 161117 199269
| 3×$\frac{4}{21}$ | $\frac{3}{5}$×$\frac{4}{15}$ | 16×$\frac{3}{8}$ | $\frac{5}{6}$×10 |
| $\frac{4}{9}$÷$\frac{8}{3}$ | $\frac{11}{12}$÷$\frac{5}{6}$ | 5÷$\frac{1}{5}$ | $\frac{5}{8}$÷15 |