Saudi Arabia 25 Halalah 1972 - Two Versions

Hello,
I have been using Numista for over a year and a half now but today I am making my first post. I was looking at Saudi Arabian coins and noticed two versions of a 1972 25 Halalah coin -- one with incorrect grammar and one with the corrected grammar on the reverse side.

According to the coin page (https://en.numista.com/catalogue/pieces2574.html), this is the corrected form,

خمس و عشرون هللة
(Twenty Five Halalas)

According to the post, خمس (five) is in the feminine grammatical form, which is correct.

According to this page (https://en.numista.com/catalogue/pieces20732.html), this coin is in the incorrect masculine form, خمسة

I have been an English-speaking American my whole life and just recently started learning Arabic, but if I'm not mistaken (and I very well could be), isn't خمسة actually the correct feminine form, and خمس is actually masculine, in this case being incorrect? Isn't هللة in the feminine form, meaning that the five in twenty five should also be in the feminine form, with them both ending in ة ? I think the two coin pages may be incorrect and have mixed up their wordings. Again, I know very little Arabic, so if someone who is more knowledgeable than me could clarify, that would be great.

Thanks!

Did you look at the documentaions joined to those two coins?

No, everything is right. In Arabic there's a linguistic feature called "polarity". For numbers between 3 and 10 you need to use the feminine form of the number for a masculine noun and vice versa:
ثلاث بنات
but
ثلاثة رجال

And therefore خمس وعشرون هللة is right.

Oh, thank you very much! I haven't heard about the "polarity" feature before.