Divisor 18089

To determine if any number is divisible by 18089, apply the "Kerry S Hall Test":

1. If your number ("X") has 11 digits or more, separate the last (smallest) 10 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 11 digits, L = 0 and therefore R = X.
2. Multiply L by 2842 and add to R.
3. Take that result and cross off its final digit (units). Take this new number and add 1809 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 18089. That is, your original number is divisible by 18089 if (and only if) Y is. Now that it's much smaller, with basic knowledge of your 18089-times tables, it should be easy to visually see if Y is divisible by 18089. If the Y is still much larger than 18089, the above process can be repeated until it does reduce to within small multiples of 18089.

Easy!