Add bc to Everyday use section

README-zh.md

@@ -201,6 +201,17 @@
 >>> 2+3
 5
 ```
+另一个方法是bc （如果你的系统上没有安装python的话)
+```                                          
+echo "2+3"|bc                                
+5                                            
+```                                          
+Specify scale for accuracy control purpse.                                                                                                                                               
+指定scale参数可以控制计算精度
+```                                          
+echo "scale=4;9/7"|bc                        
+1.2857                                       
+```  
 
 
 ## 文件及数据处理

README.md

@@ -202,6 +202,16 @@ Notes:
 >>> 2+3
 5
 ```
+Another approach is to use bc, in case you have no python installed in your system.
+```
+echo "2+3"|bc
+5
+```
+Specify scale for accuracy control purpse.
+```
+echo "scale=4;9/7"|bc
+1.2857
+```
 
 
 ## Processing files and data