Score is kept in bowling by adding the number of pins knocked down. Scores can be multiplied by accumulating strikes and spares, that is, knocking all of the pins down in one frame. A perfect game in bowling is a score of 300 through ten frames. Though a bowler may only knock down a maximum of 120 pins in a game, a score of 300 may be achieved through the additional bonus scores obtained by strikes and spares.
In general, one point is scored for each pin knocked down in bowling. If a bowler throws the ball and knocks down one pin, they score 1. If they knock down 6 pins on the second throw of the first frame, the score for frame one is (1 + 6) 7. If on the next frame, the bowler achieves a 5 and a 3, the score for frame two is (5 + 3) 8. The combined score for the first two frames of bowling is then (7 + 8) 15. The score is kept in this manner all the way through ten frames. The cumulative score at the end of ten frames of bowling is the total.
If, however, strikes and spares are added into the score, the equation differs. Though it remains simple addition, 10 pins are not simply added for a strike or a spare. If a bowler throws a strike, which is the act of knocking down ten pins on the first throw of a frame, their second throw is not necessary. After a strike, the player is awarded the 10 points for knocking down all ten pins, plus the points for the next two balls the bowler throws on the following frames. The next two balls will count toward their corresponding frames and toward the previous strike frame as well.
For instance, if a bowler is bowling a 37 at the beginning of frame four, and then throws a strike on that frame, an X is put in the score box to signify the strike. The bowler now has the previous 37, plus the strike, but the score is not added until the next two balls are thrown. If the next two balls in frame five are a 4 and a 5, these numbers are marked for frame five as a 9, and then added to the strike on frame four.
Therefore, the score after bowling frame five would be the score of the first three frames (37) plus the strike (10) plus the bonus points for the two balls that followed (9). These would be added onto frame five to equal, by frame: 37 + 19 + 9 = 65. Although the bowler only knocked down 56 pins, the bonus points from the two balls following the strike added up to 9 pins and a score of 65.
Scoring is kept the same way with a spare, except that only one additional ball is added as a bonus to the spare frame. With a series of strikes or spares, scoring remains consistent with individual strike and spare rules, though the scoring may get a little backed up in a competitve bowling game.