早教吧作业答案频道 -->其他-->
口算:(1)1+2+4+8+16+32+64+128+256+512=(2)1000001×999999=(3)(1+2+3+…+2007+2008+2007+…+3+2+1)÷2008=(4)(2005+2003+…+3+1)-(2+4+6+…+2002+2004)=
题目详情
口算:
(1)1+2+4+8+16+32+64+128+256+512=
(2)1000001×999999=
(3)(1+2+3+…+2007+2008+2007+…+3+2+1)÷2008=
(4)(2005+2003+…+3+1)-(2+4+6+…+2002+2004)=
(1)1+2+4+8+16+32+64+128+256+512=
(2)1000001×999999=
(3)(1+2+3+…+2007+2008+2007+…+3+2+1)÷2008=
(4)(2005+2003+…+3+1)-(2+4+6+…+2002+2004)=
▼优质解答
答案和解析
(1)1+2+4+8+16+32+64+128+256+512,
=(1+2+4+8+16+32+64+128+256+512)+1-1,
=(2+2+4+8+16+32+64+128+256+512)-1,
=(4+4+8+16+32+64+128+256+512)-1,
=(8+8+16+32+64+128+256+512)-1,
=(16+16+32+64+128+256+512)-1,
=(32+32+64+128+256+512)-1,
=(64+64+128+256+512)-1,
=(128+128+256+512)-1,
=(256+256+512)-1,
=(512+512)-1,
=1023;
(2)1000001×999999,
=(1000000+1)×999999,
=1000000×999999+1×999999,
=999999000000+999999;
=999999999999;
(3)(1+2+3+…+2007+2008+2007+…+3+2+1)÷2008,
=[(1+2007)×2007÷2×2+2008]÷2008,
=[2008×2007+2008]÷2008,
=2008×(2007+1)÷2008,
=2008×2008÷2008,
=2008;
(4)(2005+2003+…+3+1)-(2+4+6+…+2002+2004),
=2005+2003+…+3+1-2-4-6-…-2002-2004,
=(2005-2004)+(2003-2002)+…+(7-6)+(5-4)+(3-2)+1,
=1+1+…+1+1+1+1,
=1003.
=(1+2+4+8+16+32+64+128+256+512)+1-1,
=(2+2+4+8+16+32+64+128+256+512)-1,
=(4+4+8+16+32+64+128+256+512)-1,
=(8+8+16+32+64+128+256+512)-1,
=(16+16+32+64+128+256+512)-1,
=(32+32+64+128+256+512)-1,
=(64+64+128+256+512)-1,
=(128+128+256+512)-1,
=(256+256+512)-1,
=(512+512)-1,
=1023;
(2)1000001×999999,
=(1000000+1)×999999,
=1000000×999999+1×999999,
=999999000000+999999;
=999999999999;
(3)(1+2+3+…+2007+2008+2007+…+3+2+1)÷2008,
=[(1+2007)×2007÷2×2+2008]÷2008,
=[2008×2007+2008]÷2008,
=2008×(2007+1)÷2008,
=2008×2008÷2008,
=2008;
(4)(2005+2003+…+3+1)-(2+4+6+…+2002+2004),
=2005+2003+…+3+1-2-4-6-…-2002-2004,
=(2005-2004)+(2003-2002)+…+(7-6)+(5-4)+(3-2)+1,
=1+1+…+1+1+1+1,
=1003.
看了 口算:(1)1+2+4+8+...的网友还看了以下:
6.3÷0.021=1.5÷0.03=0.43×5=0.7×8-0.6=72÷24=5×0.7=6 2020-04-07 …
5×0.7=0.43×5=3.6÷0.9-4=240÷37≈3.6-0.36=8.1-2.2=0. 2020-04-07 …
BP神经网络高手来5.1,3.5,1.4,0.2,Iris-setosa4.9,3.0,1.4,0 2020-05-17 …
求如何把年份范围限制为1994-9999的正侧表达式?年份范围为0001-9999,匹配YYYY的 2020-06-20 …
0.1循环=1/9,0.2循环=2/9····0.8循环=8/9,0.9循环=?按照以上规律0.9 2020-07-17 …
1/9=0.111111……2/9=0.222222……3/9=0.333333……所以分母每增加 2020-07-19 …
这个正则表达式为什么能判断一年是不为闰年?我不太懂正则的语法.RegExp("^(?::([0-9 2020-07-23 …
1/9=0.11111111.2/9=0.222222.3/9=0.33333333.4/9=0. 2020-07-24 …
直接写出得数.0.6×0.8=2.4×3=3.9÷0.3=5.6÷8=0.63÷0.7=0.45÷3 2020-11-19 …
直接写数对又快.3.5×4=8.2+2.08=36÷0.01=99+1÷10=6-2.4×2=4÷0 2020-11-19 …