Description:

We need to sum big numbers and we require your help.

Write a function that returns the sum of two numbers. The input numbers are strings and the function must return a string.

Example

add("123", "321"); -> "444"
add("11", "99");   -> "110"

Notes

• The input numbers are big.
• The input is a string of only digits.
• The numbers are positives.

My solution

using System.Numerics;

public class Kata
{
    public static string Add(string a, string b)
    {
        BigInteger A = BigInteger.Parse(a);
        BigInteger B = BigInteger.Parse(b);

        return (A + B).ToString();
    }
}