问题
解答题
能用简便的要用简便算
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答案
(1)399×99+399,
=399×(99+1),
=399×100,
=39900;
(2)283-(125+83),
=283-125-83,
=283-83-125,
=200-125,
=75;
(3)1+2+3+4…+99+100,
=(1+100)+(2+99)+…+(50+51),
=101×50,
=5050;
(4)137×13+137×6+137,
=137×(13+6+1),
=137×20,
=2740;
(5)2007+2008+2009+6,
=2007+2008+2009+3+2+1,
=(2007+3)+(2008+2)+(2009+1),
=2010+2010+2010,
=2010×3,
=6030.