Sandbox
RNGdle Sandbox
Enter a number from 0 to 999,999, then edit its digits. See the score and badge change instantly, discover new patterns and try the best single-digit improvement. Lock digits to keep them fixed, revisit your steps, and save or share the whole experiment.
One digit. A new discovery.
Start with a number you can improve.
The leading slot skips 0 so the digit count stays where you put it — use the length control to change it. 1,000,000 is the only seven-digit number in range; see it here.
No available single-digit change improves this score with your current locks.
Top five available edits
Ranked by the existing score. Locked digits stay fixed; an available edit may lower the score.
524,288 · 451 points · −174
Digit 6: 7 → 8. Gains Power of two. Gains Digit sum 29. Loses All ones in binary. Loses Digit sum 28.
524,289 · 342 points · −283
Digit 6: 7 → 9. Gains Digit sum 30. Gains Semiprime. Loses All ones in binary. Loses Digit sum 28.
524,387 · 293 points · −332
Digit 4: 2 → 3. Gains Digit sum 29. Gains 6 distinct digits. Loses All ones in binary. Loses Digit sum 28.
524,987 · 279 points · −346
Digit 4: 2 → 9. Gains Descending segment. Gains Digit sum 35. Loses All ones in binary. Loses Digit sum 28.
824,287 · 273 points · −352
Digit 1: 5 → 8. Gains Digit sum 31. Gains Double pair. Loses All ones in binary. Loses Digit sum 28.
Your experiment path
Select any step to revisit it. A new edit after Undo starts a new branch of this path.
How to use it
Click any digit slot, then use ↑ and ↓ to step it, ← → to move between slots, or just type a digit. Nothing is sent anywhere — the whole range is scored in your browser from the same index the rest of the site uses.
Why the starting number is 524,287
524,287 is 219 − 1, a Mersenne prime. That makes it prime, a binary repunit and a binary palindrome simultaneously — three traits resting on one arithmetic fact. Change any digit and all three vanish together, which is the shortest possible demonstration of what this tool is for.
Local maxima
"Best single-digit edit" scores every number one edit away and reports the strongest. When it says there is none, you have found a local maximum: a number that no single digit change can improve. They are more common than they sound, and climbing out of one usually means changing two digits at once — which is where the pattern explorer is the better tool.