2*1/3+3*1/4+4*1/5+5*1/6+6*1/7.。。。。17*1/18？

2*1/3+3*1/4+4*1/5+5*1/6+6*1/7+8*1/9+9*1/10如何简便运算 【答案】:2*1/3+3*1/4+4*1/5+5*1/6+6*1/7+8*1/9+9*1/10 =1-1/3+1-1/4+1-1/5+1-1/6+1-1/7+1-/9+1-1/10 =7-(1/3+1/4+1/5+1/6+1/7+1/9+1/10) =7-(1/3+1/4+1/6+1/7+1/9+1/5+1/10) =7-(3/4+16/63+3/10) =7-(21/20+16/63) =7-(1+1/20+16/63) =7-(1+(63+20*16/63*20)) =7-1-383/1260 =5又877/1260

什么意思