To bowl a perfect game, one must roll 12 strikes in a row, which represents 120 total pins knocked down. If a bowler gets a strike in the 10th frame, he is awarded two additional rolls.
A perfect game is a score of 300 in bowling. When a bowler rolls a strike, his score for that frame is determined by the following two rolls. The bowler earns 10 pins plus the number of pins in the following two rolls. So, if a bowler rolls two strikes following the strike in the original frame, he earns 30 points for the original frame. To achieve a score of 300, the bowler must bowl a strike in every frame; the final two strikes are added to the score for the first strike in the 10th frame, but they do no accrue points on their own.