The correct answer is 4 in this case the tests are different. In the description you reach 1213, to reach 1214 you need a part of another year.

After solving (in my opinion) this puzzle, I get the same error from a test case of the "Attempt" submission.
I also think the correct answer for the test case :

p0: 1000
percent: 2.0
aug: 50
p: 1214

is 3, for 3 years.

This test case is similar to the one given in the kata's description and this description itself proposes 3 as the correct anwser. I completely agree with the demonstration of @uslu.

I don't understand how this is supposed to work. I convert the calculated population to an integer, but still get the number of years 3

The last one.

A similar case is explained in the kata's description. Read it again.

At the end of the 2nd year there will be: 
1070 + 1070 * 0.02 + 50 => 1141 inhabitants (** number of inhabitants is an integer **)

i get error on 1 test out of all and it seems to be an error - im using python.

• • • test - - -
      p0: 1000
      percent: 2.0
      aug: 50
      p: 1214

says it should take 4 years when it only takes 3
1000 * 1,02 + 50 = 1070
1070 * 1,02 + 50 = 1141,4
1141,4 * 1,02 + 50 = 1214,228

goddamn chemistry :D

careful, there are exceptions to the rules. It's in the link too

(sry im new at this)
i used python 3.8
i see it in both sample and attempt tests
The issue perhaps is more clear in element Og:
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f14 6s2 6p6 6d10 7s2 7p6

Where are you seeing the wrong order (sample tests, attempt tests)? In which language?

i thought i did "This gives the following order for filling the orbitals:

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, (8s, 5g, 6f, 7d, 8p, and 9s)"

3d after 4s and before 4p was my point in the first post - dont know if this issue persist elsewhere

No, read the link.

order is mistaken? :Br "1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p5....",
should be :Br "1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5...."

order isnt just ssss, pppp, dddd, ffff. Don't know if this issue is systematic. (i havent solved the coding problem, just made some print statements)