OP solved it, closing

It's 4 breaks to get 5, not 4 pieces of 1x5 blocks, and then 4 breaks for each of those, that's 24. Or you could break it into 1x5 and 5 4x5 pieces, and you'll still have 24 breaks: 1 + 4 + 4 + 5 * 3 = 24

I dont agree. No one would try to break a 1x1 out of a 5x5. I hope nearly everyone would either first break 5x5 into 1x5 and 4x5 or directly into 5 times 1x5, which would only be 4 breaks. Therefore the rest would be broken in to each 1x1 with each 4 further breaks. Therefore resulting in 4 times 4 breaks, so 16 breaks total.

You did it wrong on paper.

you can set two values for indexing
like
i = 0
k = 3
so you can index like
strarr[i:k]

First of all, what you think is O(n) might actually not be O(n), depending on your approach.
But generally yes, you need something better than linear.

Please provide a clear example of alleged failed test, it's very probable you are mistaken. Don't raise issues lightly just because you just don't understand something. Without more elements from you this issue will probably be closed without follow-up some day. See there: https://docs.codewars.com/training/troubleshooting/

What language are you talking about? Any examples?

assertFalse("1  is not prime", Prime.isPrime(1));

And 1 is not a prime number: https://blogs.scientificamerican.com/roots-of-unity/why-isnt-1-a-prime-number/

Please read the description again:

Per Wikipedia, a prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself.