=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+……+1/99-1/100=1-1/100=99/100
1/2+1/6+1/12+1/20+...+1/9900=1/1*2+1/2*3+1/3*4+...+1/99*100=1-1/2 +1/2-1/3 + 1/3-1/4 +... +1/99-1/100=1-1/100=99/100