1+1/1+1/2+1/3+1/4.......
diverges, by Cauchy condensation.
1+1/1^2+1/2^2+1/3^2+1/4^2...... converges.
Hmmm! METHOD? I don't know which exam asks that? But You can use comparison test or ratio test to find out whether it is convergent or divergent. 1+1/1^2+1/2^2+1/3^2+1/4^2+.....=1+π^2/6 (1+ (pi^2)/6), but don't know the method for it.