1/2+1/6+1/12+…+1/n(n+1)=2003/2004
1-1/2+1/2-1/3+1/3-1/4+...+1/n-1/(n+1)=2003/2004
1-1/(n+1)=2003/2004
1/(n+1)=1/2004
n+1=2004
n=2003
1/2+1/6+1/12+…+1/n(n+1)=2003/2004
1-1/2+1/2-1/3+1/3-1/4+...+1/n-1/(n+1)=2003/2004
1-1/(n+1)=2003/2004
1/(n+1)=1/2004
n+1=2004
n=2003