Simplifying fractions in C#

Question

I have made a console app that adds and subtracts fractions, I have added a function to simplify:

    public static Numbers Add(Numbers n1, Numbers n2)
    {
        int den1;
        int num1;
        int num2;
        int dsimp;
        int nsimp;
        int numtop;
        num1 = n1.Numerator * n2.Denominator;
        num2 = n2.Numerator * n1.Denominator;
        den1 = n1.Denominator * n2.Denominator;
        numtop = num2 + num1;

        if (numtop == 0)
        {
            return new Numbers(0);
        }
        if (numtop % n1.Denominator == 0)
        {
            nsimp = numtop / n1.Denominator;
            dsimp = den1 / n1.Denominator;
            return new Numbers(nsimp, dsimp);

        }

        else
        {
            return new Numbers(numtop, den1);
        }
    }

When I put in 1/2 + 4/8 it simplifies it all perfectly the way I tell it to, but, it gives me 8/8. This needs to be simplified to 1/1. How do I get it to simplify what has already been simplified to the lowest possible fraction?

Answer 1

Divide the numerator and denominator by the GCD (greatest common divisor) of the numerator and denominator.

Eg:

Start with say 12/8. The GCD is 4. Thus 3/2.