I am good in math or i am good at math. which is correct?

Answer 1

Both "I am good in math" and "I am good at math" are commonly used and generally accepted. However, the more technically correct phrase is "I am good at math." The preposition "at" is typically used to indicate proficiency or skill in a subject or activity, while "in" is more commonly used to refer to being physically located within something.

Answer 2

both can be, it depends whether you use 'maths' to mean 'mathematics' (i.e. the subject), or maths class/lesson. you can't be good in mathematics (you should say you are good at mathematics), but you could be good in maths class/ in you maths lesson.

Generally speaking, You would use: "I am good at math".

"I am good in/at maths" would both be incorrect. There is no need to add the s at the end of the word "math", because math is already the general term for the different types of mathematics.