My way of coding Javascript is going on good direction? Please feedback

I am very thankful to @camperextraordinaire,. He is my best mentor. Now, I have written a simple calculation program. I do my best to write the code in a good way. I used for loop to reduce the repetition of the code. As well used different functions to manage the codes. As I am a very basic learner, I wish to get suggestions, if this is going on good direction.

Thank you very much.

@camperextraordinaire Thank you sir. I am going to do it. A good topic for me to study for today. After doing it I will let you know in the comment.

Thank you!

@camperextraordinaire . I used .toFixed(2) to fix this issue. Is this the correct way? Thank you very much .

Hey!

I like your project, great work!

One thought about your comments:
Most of your comments are like

// Multiply Function
function multiply() {...}

I see no benefits in doing this. The function name is already saying what the function will do, so the comment adds redundant information.

thank you very much @miku86 . I changed it and keep comment for all functions once like
// Calclation Functions

Thank you very much for your feedback and suggestion.

@camperextraordinaire, Sir, I googled lots and still googling but, could not got the idea to fix this round of errors. I still want to to try more, just want one hint from you, Do we need to write the program for it? or we have any inbuilt function.
Thank you