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计算(1)21+22+23+…30+31+32=;(2)100-99+98-97+96-95+94-93+…+4-3+2-1=;(3)5+10+15+…90+95+100=;(4)486+327+514+223=;(5)1652-(1321+252)=;(6)8+98+998+398=.

题目详情
计算
(1)21+22+23+…30+31+32=______;
(2)100-99+98-97+96-95+94-93+…+4-3+2-1=______;
(3)5+10+15+…90+95+100=______;
(4)486+327+514+223=______;
(5)1652-(1321+252)=______;
(6)8+98+998+398=______.
▼优质解答
答案和解析
(1)21+22+23+…30+31+32,
=(21+32)+(22+31)+(23+30)+(24+29++(25+28)+(26+27),
=53×6,
=318;

(2)100-99+98-97+96-95+94-93+…+4-3+2-1,
=(100+98+96+94+…+4+2)-(99+97+95+93+…+3+1),
=(25×100+50)-(100×25),
=2550-2500,
=50;

(3)5+10+15+…90+95+100,
=(5+95)+(10+90)+(15+85)+(20+80)+(25+75)+(30+70)+(35+65)+(40+60)+(45+55)+50+100,
=10×100+50,
=1050;

(4)486+327+514+223;
=(486+514)+(327+223),
=1000+550,
=1550;

(5)1652-(1321+252),
=1652-1321-252,
=1652-252-1321,
=1400-1321,
=79;

(6)8+98+998+398,
=(10-2)+(100-2)+(1000-2)+(400-2),
=(10+100+1000+400)-(2+2+2+2),
=1510-8,
=1502.