ok, took a look at someone else's thread below and discovered it's a newline issue.

This is a rank 7 kata. Lots of folks are gonna come across this who are just learning to code. You're setting a ton of people up for failure here with this trick.

I can take being a dummy for a sec, I've been coding for a while. But for other folks, highly recommend adding a line at the end of this description like "hint: consider newlines" or better yet, just adding a case to the visible tests that includes several newlines at the end.

Similar issue to others. "Expected: false, instead got: true" for "567890".

If this case should return false, the description is broken, because full conditions are not explained.

This test case is exactly six digits, and contains only numbers -- per the description, 'true' should be the answer.

Very cool kata, glad it on here -- haven't finished yet, but wanted to suggest for teaching purposes:

Could add a clear note at the top that this is more about math & performance-thinking than about coding-as-language. Agree with another comment that 7kyu rating is steep. I understand that the mathiness/algorithm-generating nature of the problem is communicated through the last line "Your solution has to support 0≤n≤10^60 Brute-forcing will not work!" but since it's the very last line on the pg, I'd guess a lot of ppl miss/skip over it until they've already started, or might not understand at the 7kyu level what "brute-forcing will not work" means.