Adorable!
I think as long as she understands both approaches, it's fine.
L.C.M is an important concept that is among the evaluation criteria of her teacher apparently, hence the low marks.
The good news is, it won't matter how she solves the problems in the future (that's when if she doesn't choose Computing as her major later on.) 😉
Thank you for your reassuring remarks. I agree with you on the point of evaluation criteria, but this teaching approach can demoralize students and eventually lead to disinterest in the subject. However, that is how it is. So let's hope for the best for their future and learning.