public static boolean isNumberFirst(int numToCheck){
        if (numToCheck == 1){
            return false;
        }

        int[] MFB = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31};
        int divisor = 0;
        int i = 0;
        while ((divisor ^ 2) < numToCheck){
            if (i < MFB.length) {
                divisor = MFB[i];
            } else {
                divisor += 2;
            }
            if (divisor == numToCheck){
                i++;
                continue;
            }
            int rest = numToCheck % divisor;
            if (rest == 0){
                return false;
            }
            i++;
        }
        return true;
    }