Why is 1 term wrong [closed]

A module takes __ and the work is very intensive... The correct answer is "a term" or "one term", I wrote "1 term" and is marked wrong, even though not long after this question "2 modules" is one of the correct answer.

From: from one of the IELTS question.https://ieltscat.xdf.cn/mock/analyze/listen/A5DAEBF566DF7EFC/26

It's quite uncommon to write "one" as "1", except when talking about the number "1" itself.

As an example, we might write: "He wrote one number, which was the number 1, and below that he wrote two more numbers, the numbers 2 and 3."

A Google Ngrams search shows that "lasted one year" is much more common than "lasted 1 year".

I don't think I would say that "A module takes 1 term" is wrong, but in most contexts, it looks like lazy writing. "A module takes one term" looks much better.