18．口算．
0 161014 161022 161028 161032 161038 161040 161044 161050 161052 161058 161064 161068 161070 161074 161080 161082 161088 161092 161094 161098 161100 161104 161106 161108 161109 161110 161112 161113 161114 161116 161118 161122 161124 161128 161130 161134 161140 161142 161148 161152 161154 161158 161164 161170 161172 161178 161182 161184 161190 161194 161200 161208 199269
| 120×2= | 121×2= | 24×6= | 200×16= | 200×16= |
| 0×120+24= | 21×60+6= | 15×40-50= | 25×40+45= | 125×8+21= |