Divisor 12487

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

The "Dimo Test" for Divisibility by 12487

To determine if any number is divisible by 12487, apply the "Dimo Test":

  1. If your number ("X") has 6 digits or more, separate the last (smallest) 5 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 6 digits, L = 0 and therefore R = X.
  2. Multiply L by 104 and add to R.
  3. Take that result and cross off its final digit (units). Take this new number and subtract 3746 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 12487. That is, your original number is divisible by 12487 if (and only if) Y is. Now that it's much smaller, with basic knowledge of your 12487-times tables, it should be easy to visually see if Y is divisible by 12487. If the Y is still much larger than 12487, the above process can be repeated until it does reduce to within small multiples of 12487.

Easy!