问题
解答题
(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.
答案
(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.