Divisor 18149

Prime Number:
Yes!
Divisibility test:
The "Jun Siang Cheah Test"
Test Discovered by:
Matt Parker
Date:
11/11/2024

The "Jun Siang Cheah Test" for Divisibility by 18149

To determine if any number is divisible by 18149, apply the "Jun Siang Cheah Test":

  1. If your number ("X") has 8 digits or more, separate the last (smallest) 7 digits from the rest. This makes two smaller numbers, call them Left and Right (note: don't add in trailing zeros to L). If there are fewer than 8 digits, L = 0 and therefore R = X.
  2. Multiply L by 99 and subtract this from R.
  3. Take that result and cross off its final digit (units). Take this new number and add 1815 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 18149. That is, your original number is divisible by 18149 if (and only if) Y is. Now that it's much smaller, with basic knowledge of your 18149-times tables, it should be easy to visually see if Y is divisible by 18149. If the Y is still much larger than 18149, the above process can be repeated until it does reduce to within small multiples of 18149.

Easy!