Question

小学六年级数学题[用简便方法计算] 2/1+6/1+12/1+20/1+30/1+42/1+56/1+72/1=?5/4？

Answer 1

1、1/2+1/6+1/12+……+1/72
=1-1/2+1/2-1/3+1/3-1/4+……+1/8-1/9
=1-1/9
=8/9
2、4/5×4+2/5×2+1/5×16
=1/5×（16+4+16）
=1/5×36
=36/5
2010/2009x2009
=2009×2009/2010
=（2010-1）×2009/2010
=2009-2009/2010
=2008又1/2010,2,小学六年级数学题
[用简便方法计算]
2/1+6/1+12/1+20/1+30/1+42/1+56/1+72/1=?
5/4x4+5/2x2+5/1x16=?
2010/2009x2009=?