The rules of duckpin bowling are easy to learn, and once you become acquainted with the basic rules of play, you will be ready to roll in no time at all. A regulation game consists of 10 frames, or boxes. A bowler is allowed up to three balls per frame to knock down as many pins as possible If all ten pins are knocked down by the first ball in any frame, it is called a 'Strike' and is usually symbolised on the score sheet with an X. A Strike counts as 10 plus the total of the pins knocked down with the next two balls that are rolled. If all ten pins are knocked down with the first two balls in any frame, it is called a 'Spare', and is usually symbolised with a diagonal line on the score sheet. A spare counts as 10 plus the total of the pins knocked down on the next ball rolled. If the bowler fails to get a strike or a spare, he/she rolls the third ball to get the remaining pins and the total pins knocked down on three balls becomes the score for that frame. Score is kept in an accumulated manner, left to right, through the 10 frames, with a perfect game being 300. Information is from the brochure of the Duckpin Bowling Proprietors of America. [from http://www.robinsweb.com/duckpin/duckpin-howto.html]