13．脱式计算．（能简算的要简算）
| 2-0.56-0.44 | 0.8+1.7+0.2 | 15-5÷12 |
| 7.69×2.1+2.1×1.31+2.1 | 18-（1.4+1.25×2.4） | 7.2÷1.6+0.8 |
11．直接写得数．
0 157854 157862 157868 157872 157878 157880 157884 157890 157892 157898 157904 157908 157910 157914 157920 157922 157928 157932 157934 157938 157940 157944 157946 157948 157949 157950 157952 157953 157954 157956 157958 157962 157964 157968 157970 157974 157980 157982 157988 157992 157994 157998 158004 158010 158012 158018 158022 158024 158030 158034 158040 158048 199269
| 2.03+3.7= | 0.125×8= | 8-2.5= | （0.2-0.2）×4.8= | 427×99= |
| 0.96÷0.3= | 2.5×12= | 24÷4+56÷4= | 8÷0.4= | 3b-b= |