Divisor 7559
- Prime Number:
- Yes!
- Divisibility test:
- The "Raymond Savoie Test"
- Test Discovered by:
- Matt Parker
- Date:
- 11/11/2024
The "Raymond Savoie Test" for Divisibility by 7559
To determine if any number is divisible by 7559, apply the "Raymond Savoie Test":
- 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.
- Multiply L by 557 and subtract this from R.
- Take that result and cross off its final digit (units). Take this new number and add 756 times the digit you just crossed off. Call this final result "Y".
- Y will be much smaller than X, but we have preserved divisibility by 7559. That is, your original number is divisible by 7559 if (and only if) Y is. Now that it's much smaller, with basic knowledge of your 7559-times tables, it should be easy to visually see if Y is divisible by 7559. If the Y is still much larger than 7559, the above process can be repeated until it does reduce to within small multiples of 7559.
Easy!