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(1)1.25×16(2)3.15+2.64+1.36+6.85(3)14.28-1.5×0.3-3.55(4)1-2+

来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/05/22 23:49:50
(1)1.25×16
(2)3.15+2.64+1.36+6.85
(3)14.28-1.5×0.3-3.55
(4)1-2+3-4+5-6+7-8…+2001-2002+2003-2004+2005.
(1)1.25×16
=1.25×8×2
=10×2
=20
(2)3.15+2.64+1.36+6.85
=(3.15+6.85)+(2.64+1.36)
=10+4
=14
(3)14.28-1.5×0.3-3.55
=14.28-0.45-3.55
=14.28-(0.45+3.55)
=14.28-4
=10.28
(4)1-2+3-4+5-6+7-8…+2001-2002+2003-2004+2005
=1+(-2+3)+(-4+5)+(-6+7)+…+(-2002+2003)+(-2004+2005)
=1+1+1+…+1
=1+(2005-1)÷2
=1003.