The first and 2nd answer are different because in the first one the circle is open and in the 2nd one the circle is closed. When the circle is open it means that the number that the circle is on is not a part of the asnwer. This is represented by < or > signs. When the circle is closed it means the number is included in the answer. This is represented by the symbol.
You can see that this sequence is geometric so you need to know the geometric sequence which is and if you plug in every thing you get = which would be which is 316,912,650,057,057,350,374,175,801,344
All you have to do to simplify a number written in scientific notation is to move the decimal place to the left (if the number is negative) and to the right (if the number is positive).