Divisor 18313

Prime Number:
Yes!
Divisibility test:
The "Amy ๐Ÿ’œ Test"
Test Discovered by:
Matt Parker
Date:
11/11/2024

The "Amy ๐Ÿ’œ Test" for Divisibility by 18313

To determine if any number is divisible by 18313, apply the "Amy ๐Ÿ’œ 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 Left and Right (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 322 and add to R.
  3. Take that result and cross off its final digit (units). Take this new number and add 5494 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 18313. That is, your original number is divisible by 18313 if (and only if) Y is. Now that it's much smaller, with basic knowledge of your 18313-times tables, it should be easy to visually see if Y is divisible by 18313. If the Y is still much larger than 18313, the above process can be repeated until it does reduce to within small multiples of 18313.

Easy!