1. 用简便方法计算。                                               
(1) 394+1286+406                                                       
(2) 197+121+169+56+444                                                           
(3) 442-103                                                               
(4) 728-598                                                    
(5) 318+274+182+26                                                      
(6) 539+(61+258)+l42                                                   
(7) 51+142+49+58                                                 
(8) 36+79+121+264                                                     
【考点】
整数加法交换律; 整数加法结合律;
【答案】

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