Divisor 24697

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

The "Stuart Radforth Test" for Divisibility by 24697

To determine if any number is divisible by 24697, apply the "Stuart Radforth 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 1212 and add to R.
  3. Take that result and cross off its final digit (units). Take this new number and subtract 7409 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 24697. That is, your original number is divisible by 24697 if (and only if) Y is. Now that it's much smaller, with basic knowledge of your 24697-times tables, it should be easy to visually see if Y is divisible by 24697. If the Y is still much larger than 24697, the above process can be repeated until it does reduce to within small multiples of 24697.

Easy!