1/2 × 1/5 +1/3 ×1/6+1/4×1/7+1/5×1/8+1/6×1/9+1/7×1/10

巧算：(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4+1/5+1/6)-(1+1/2+1/3+1/4+1/5+1/6)*(1/2+1/3+1/4+1/5)(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4+1/5+1/6)-(1+1/2+1/3+1/4+1/5+1/6)*(1/2+1/3+1/4+1/5)===== ((1/2)-1)*((1/3)-1)*((1/4)-1)*((1/5)-1)*((1/6)-1)*((1/7)-1)*((1/8)-1)*((1/9)-1)*((1/10)-1) 1+1+1+1+11+-1-1-1-1-2-3-4-5-6等于 1-1/2+1/3-1/4+1/5-1/6+1/7.-1/50=? 简算：1/1*2+1/2*3+1/3*4+1/4*5+1/5*6 1 2 3 5 6 (1+1/2)*(1+1/4)*(1+1/6)*.*(1+1/20)*(1-1/3)*(1-1/5)+(1-1/7)*.*(1-1/2 1-1/2+1/3-1/4+1/5-1/6+…+1/15=23*[1/( )+1/( )+1/( )+1/( )] 1／6、1／3、1／2（ ）、5／6、1. 1/6,1/3,1/2,(),5/6,()探索规律, 6/1 3/1 2/1 ( ) 6/5 ( ); / 等于除号 1+1+1+1+1-5+5-5+1+1-2+3+3+3+3-6-3-3等于多少? 1+1+1+1+1+1+1+1+1+2+5+4+8+3+6+2+1+4等于多少? 1*1/2+1/2*1/3+1/3*1/4+1/4*1/5+1/5*1/6+1/6*1/7用简便方法怎么做? 9*(1-1/2)*(1-1/3)*(1-1/4)*(1-1/5)*(1-1/6)*(1-1/7)*(1-1/8)*(1-1/9)怎样简便计算 (1+2/1)*(1+4/1)*(1+6/1)*...*(1+20/1)*(1-3/1)*(1-5/1)*(1-7/1)*...*(1-21/1)等于多少 数独六宫格 ++++1+ 2+3+++ +++5+6 ++5+++ 6++++2 ++++1+ 1+1/2+1/3+1/4+1/5+1/6+.+1/n极限多少?