I understand  ,every student has some weak points or topics. In your case , i assume you find the scientific notations topic hard . In that case , i suggest you to watch videos of this topic and practice more on this topic to get this topic very clear . Andif you still find it hard , you can leave it instead of spending more of your time on it as there are some topics which you can leave on your own , iff you are comfortable well enough with other topics.

Keep trying and working hard.