Question

小学数学1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9+1/10=？

小学数学

1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9+1/10=？
急需

Answer 1

1/2+1/3+1/4+1/5+1/6+1/10+1/9+1/8+1/7
= 30/60+ 20/60+ 15/60+ 12/60+ 10/60+ 6/60+ 8/72+ 9/72+ 1/7
= 50/60+ 27/60+ 16/60 +17/72 +1/7
= 93/60+ 85/360+ 1/7
= 558/360+ 85/360+ 1/7
= 643/360+ 360/2520
= 4501/2520+ 360/2520
= 4861/2520

看到这里，我们就应该知道，角度、时间……这些用的六十进制，就是为了二等分、三等分、四等分、五等分、六等分、十等分……公倍数都是60，像你提问这样的题目，今后就可以采用60进制，算得方便一些。

2、3、4、5、6、7、8、9、10，最小公倍数是7*8*9*5= 2520，你学会了吗？祝你学习进步！

Answer 2

1/2+1/3+1/4+1/5+1/6+1/10+1/9+1/8+1/7
= 30/60+ 20/60+ 15/60+ 12/60+ 10/60+ 6/60+ 8/72+ 9/72+ 1/7
= 50/60+ 27/60+ 16/60 +17/72 +1/7
= 93/60+ 85/360+ 1/7
= 558/360+ 85/360+ 1/7
= 643/360+ 360/2520
= 4501/2520+ 360/2520
= 4861/2520

Answer 3

1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9+1/10+1/11
=1/2+1/3+1/2*1/2+1/5+1/2*1/3+1/7+1/2*1/2*1/2+1/3*1/3+1/2*1*5
=1/2(1+1/2+1/3+1/4)+1/3(1+1/3)+1/5(1+1/2)+1/7
=1/2*25/12+1/3*4/3+1/5*3/2
=25/24+5/3+3/10+1/7
=25/24+40/24+31/70
=65/24+31/70
=2647/840 貌似没有捷径可寻

Answer 4

1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9+1/10=（1/2+1/4+1/8）+（1/3+1/6+1/9）+（1/5+1/10）+1/7=7/8+5/9+3/10+1/7=47/40+44/63=4721/2520

Answer 5

=4861/2520=1.92896.....(省略 不是循环)