1/2+1/6+1/10+1/12+1/20+1/30+1/42+.+1/2008*20091/2+1/6+1/10+1/12+1/20+1/30+1/42+.1/2008*2009=?要用简便方法计算

2/1 3/1 4/1 5/1 6/1 8/1 10/1 12/1 15/1 20/1 1/2+1/4+1/6+1/8+1/10+1/12等于多少? 1/2+1/4+1/6+1/8+1/10+1/12如何计算?简便运算 (1/2+1/4+1/6+1/10+1/12+1/60)/(1+1/3+1/5+1/10+1/15+1/30) 1/2+1/6+1/10+1/12+1/20+1/30+1/42+.+1/2008*20091/2+1/6+1/10+1/12+1/20+1/30+1/42+.1/2008*2009=?要用简便方法计算 (1+1/3+1/5+1/10+1/15+1/30)/(1/2+1/4+1/6+1/12+1/20+1/60)(用简算) (1+1/3+1/5+1/10+1/15+1/30)/(1/2+1/4+1/6+1/12+1/20+1/60)=​?简便计算方法 (1+1/3+1/5+1/10+1/15+1/30)/(1/2+1/4+1/6+1/12+1/20+1/60)=​?简算 1/2+1/6+1/12+1/20.+1/380 2%1+6%1+12%1+20%1+30%1 1/2+1/6+1/12+1/20+1/30 1/2-1/6-1/12-1/20-...-1/110 1/2,-1/6,1/12,-1/20,1/30 2/1+6/1+12/1+24/1+48/1 1/2+1/6+1/12+1/20+.1/90 2/1+6/1+12/1+20/1+...+2450/1 （1/2+1/4+1/6+1/8）-（1/3+1/6+1/9+1/12）+（1/4+1/8+1/12+1/16）-（1/5+1/10+1/15+1/20）快 (1/2+1/4+1/6+1/8)-(1/3+1/6+1/9+1/12)+(1/4+1/8+1/12+1/16)-(1/5+1/10+1/15+1/20)=