(1)26.67+72.8+2.33+4.2, =(26.67+2.33)+(72.8+4.2), =29+77, =106; (2)125×32×25, =(125×8)×(4×25), =1000×100, =100000; (3)300-123+75-77, =(300+75)-(123+77), =375-200, =175; (4)(278-78)÷(35+15), =200÷50, =4; (5)16×17+16×82+16, =16×(17+82+1), =16×100, =1600; (6)280×36+28×640, =28×360+28×640, =28×(360+640), =28×1000, =28000. |