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巧算(1)1.33-0.76+5.67-2.24(2)0.25×3.75+0.75×3.75(3)1.25×2.5×8×0.4(4)1+5+9+13+…+3997+4001.

题目详情
巧算
(1)1.33-0.76+5.67-2.24

(2)0.25×3.75+0.75×3.75
(3)1.25×2.5×8×0.4 (4)1+5+9+13+…+3997+4001.
▼优质解答
答案和解析
(1)1.33-0.76+5.67-2.24,
=(1.33+5.67)-(0.76+2.24),
=7-3,
=4;

(2)0.25×3.75+0.75×3.75,
=(0.25+0.75)×3.75,
=1×3.75,
=3.75;

(3)1.25×2.5×8×0.4,
=(1.25×8)×(2.5×0.4),
=10×1,
=10;

(4)1+5+9+13+…+3997+4001,
=(1+4001)+(5+3997)+…+(1997+2005)+2001,
=4002×500+2001,
=2001000+2001,
=2003001.