If I buy a bitcoin a bitcoin for 10000 dollars, and sell for 10200
Obviously I have gained 200 Usd.
But then out of the gain I must pay commision, if this has happened what exchange would have been least commision?
There is no one answer to this question. However, I would try Binance. This is the best-trusted exchange with the lowest commissions. Sometimes, it is better to make exchange "chains" - include in your financial operation. In any case, Binance will work. As I do remember, you will have to pay 0.1% commission only which is lower than other platforms offer.