Find the sum of the first n term (I)3+33+333...
(ii)4+44+444...

You can write it down as:

(3 x 1) + [(3 x 10) + (3 x 1)] + [(3 x 100) + (3 x 10) + (3 x 1)] +... + [(3 x 10^n) + (3 x 10^(n-1)) +... + (3 x 1)]

And same for the other.