Divisor 6353

To determine if any number is divisible by 6353, apply the "Greg Test":

1. If your number ("X") has 10 digits or more, separate the last (smallest) 9 digits from the rest. This makes two smaller numbers, call them L^eft and R^ight (note: don't add in trailing zeros to L). If there are fewer than 10 digits, L = 0 and therefore R = X.
2. Multiply L by 318 and subtract this from R.
3. Take that result and cross off its final digit (units). Take this new number and add 1906 times the digit you just crossed off. Call this final result "Y".
4. Y will be much smaller than X, but we have preserved divisibility by 6353. That is, your original number is divisible by 6353 if (and only if) Y is. Now that it's much smaller, with basic knowledge of your 6353-times tables, it should be easy to visually see if Y is divisible by 6353. If the Y is still much larger than 6353, the above process can be repeated until it does reduce to within small multiples of 6353.

Easy!