Why "learned" not "learnt"

Test No. [color=blue]errors/inter-8 “Tenses”, question 1

I have learn many things in my class today and now I can do my homework without any problems.

(a) learn
(b) things
© do
(d) any

Test No. [color=blue]errors/inter-8 “Tenses”, answer 1

I have learned many things in my class today and now I can do my homework without any problems.

Correct entry: learned
The error was: (a) learn

You have [color=green]found the error but your entry is [color=red]incorrect.
I have learnt many things in my class today and now I can do my homework without any problems.

Hi Igor,

Many thanks for brining up that issue. You right - both spellings are correct, ‘learnt’ as well as ‘learned’. We’ll make the appropriate changes.[YSaerTTEW443543]

TOEIC listening, question-response: What did you do with my pen?[YSaerTTEW443543]