| (230+770)+450230+450+770+550 78+(89+11)3×7+3×15 125×8+10×889+78+11 (7+15)×3586-135-42 586-(135-42)(125+10)×8. |
| (1)(230+770)+450, =1000+450, =1450; (2)230+450+770+550, =(230+770)+(450+550), =1000+1000, =2000; (3)78+(89+11), =78+100, =178; (4)3×7+3×15, =3×(7+15), =3×22, =66; (5)125×8+10×8, =1000+80, =1080; (6)89+78+11, =(89+11)+78, =100+78, =178; (7)(7+15)×3, =22×3, =22; (8)586-135-42, =586-(135+42), =586-177, =409; (9)586-(135-42), =586-93, =493; (10)(125+10)×8, =125×8+80, =1000+80, =1080. |
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