3．口算
| 120×60= | 23万+17万= | 110×50= |
| 198亿-120亿= | 220×20= | 130×40= |
18．口算．
0 157944 157952 157958 157962 157968 157970 157974 157980 157982 157988 157994 157998 158000 158004 158010 158012 158018 158022 158024 158028 158030 158034 158036 158038 158039 158040 158042 158043 158044 158046 158048 158052 158054 158058 158060 158064 158070 158072 158078 158082 158084 158088 158094 158100 158102 158108 158112 158114 158120 158124 158130 158138 199269
| 1-0.25= | 3.4+1.56= | 3.3-0.8= | 5.7+8.4= |
| 15×0.2= | 3.26÷100= | 0.25×4= | 10×2÷10×2= |