用竖式计算（带△验算）．
| 3.906+0.66= | △125.5-87.55= | 4.6×3.07= | △21.6÷0.36= |
直接写出得数
1÷ = |  + = |  ÷ = | ÷3= | ×= |
 - = |  ÷7= |  ÷ = | 4× = |  ÷8= |
 ×= | ÷ = |  ÷0.5= | 5× = | - = |
 ×0= | 0.3× = | ÷ = |  ÷4= | +0.5= |
| 3.906+0.66= | △125.5-87.55= | 4.6×3.07= | △21.6÷0.36= |
| 1÷= | += | ÷= | ÷3= | ×= |
| -= | ÷7= | ÷= | 4×= | ÷8= |
| ×= | ÷= | ÷0.5= | 5×= | -= |
| ×0= | 0.3×= | ÷= | ÷4= | +0.5= |
如图是一个残破的钟面．用软尺量得其边沿的弧长是15.7厘米，你能出它的完整的钟面的面积吗？