The Hundred game

Find the correct number to score always ONE HUNDRED in a race against the time.
There are a hundred levels in three different game modes (easy, medium, hard) in which you should be the faster to gain as much point as possible.
On the halfway level things getting more complicated: beside the numbers you must
also identify the correct operator that allows you to score always ONE HUNDRED.
Finally… there is a surprise for the most difficult level.
Have fun!