To summarize. If you have a strong application, these scores can help you stand out. If you have a borderline application, they can, perhaps, help you be considered. However, if your application is otherwise weak, they will likely not accept you based on these score alone.
These type of awards have the strongest boost if you are looking to major in Math or in a math heavy discipline like engineering or physics. They will be good for every college which has holistic admissions and therefore considers achievements which are not part of your transcript. They will likely attract more attention at college which have strong math/engineering/physics programs, since these colleges tend to have AOs who are more familiar with these competitions. However, it is a very strong extracurricular achievement.
Finally - only major in math if you love love love love love math. I mean, things like engaging in mathematics challenges or solving math problems in your spare time.