Let's use PEMDAS.
First we look for parentheses there are parentheses so we have to simplify them
6.022x1023=6160.506 our problem now becomes 6160.506x2.58
Next we look for exponents there are no exponents so we move on.
Next we look for multiplication there is multiplication so we have to simplify.
6160.506x2.58=15894.10548