Divisor 11831

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

The "Matt Fisher Test" for Divisibility by 11831

To determine if any number is divisible by 11831, apply the "Matt Fisher 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 Left and Right (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 1053 and add to R.
  3. Take that result and cross off its final digit (units). Take this new number and subtract 1183 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 11831. That is, your original number is divisible by 11831 if (and only if) Y is. Now that it's much smaller, with basic knowledge of your 11831-times tables, it should be easy to visually see if Y is divisible by 11831. If the Y is still much larger than 11831, the above process can be repeated until it does reduce to within small multiples of 11831.

Easy!