Divisor 13463

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

The "Spuddy Test" for Divisibility by 13463

To determine if any number is divisible by 13463, apply the "Spuddy 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 3009 and subtract this from R.
  3. Take that result and cross off its final digit (units). Take this new number and add 4039 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 13463. That is, your original number is divisible by 13463 if (and only if) Y is. Now that it's much smaller, with basic knowledge of your 13463-times tables, it should be easy to visually see if Y is divisible by 13463. If the Y is still much larger than 13463, the above process can be repeated until it does reduce to within small multiples of 13463.

Easy!