Question

Write an interactive program that adds two integers of up to 50 digits each (Represents integer as an array of digits).

Answer 1

You can use something like bigInteger or bigNumber for Java IIRC.
http://www.cis.upenn.edu/~bcpierce/courses/629/jdkdocs/api/java.math.BigInteger.html

Or you could just store the arrays as strings and work through the logic like that