Candlepin bowling was developed in 1880 in Worcester, Massachusetts, by Justin White, a local bowling center owner, some years before both the standardization of the tenpin bowling sport in 1895. The main differences between candlepin bowling and the predominant tenpin bowling style are that each player uses three balls per frame, rather than two (see below); the balls are much smaller (11.43 cm or 4½ in diameter) with each ball weighing as much as only one candlepin and without finger holes; the pins are thinner (hence the name "candlepin"), and thus harder to knock down; and the downed pins (known as "wood") are not cleared away between balls during a player's turn. Because of these differences, scoring points is considerably more difficult than in tenpin bowling, and the highest officially sanctioned score ever recorded is 245 out of a possible 300 points.
One point is scored for each pin that is knocked over. So, in a hypothetical game, if player A felled 3 pins with their first ball, then 5 with their second, and 1 with the third, they would receive a total of 9 points for that box. If player B knocks down 9 pins with their first shot, but misses with their second and third, they would also score 9. In the event that all ten pins are felled by any one player in a single box, by no more than two throws (just as in tenpins) bonuses are awarded for a strike or spare. A strike is achieved with just the first delivery downing all ten pins, with a spare needing two throws, again just as in the tenpin sport. If all ten pins are felled by rolling all three balls in a box, the result is a Ten or ten-box, usually marked by an X (as in the Roman numeral for ten) but no additional points are awarded. (In tenpin bowling, a strike is often scored with an X). The maximum score in a game is 300. This is scored by bowling 12 strikes: one in each box, and a strike with both bonus balls in the 10th box. In this way, each box will score 30 points (see above: scoring: strike). This scoring system, except for the scoring sheet's appearance and the graphic symbols used to record strikes, spares and 10-boxes, is identical to that of duckpins, as it is the other major form of bowling that uses three balls per frame. Strike When all 10 pins are knocked down with the first ball (called a strike), a player is awarded 10 points, plus a bonus of whatever they score with their next 2 balls. In this way, the points scored for the two balls after the strike are scored twice. Example: Box 1, ball 1: 10 pins felled (strike) Box 2, ball 1: 3 pins felled Box 2, ball 2: 6 pins felled Box 2, ball 3: 1-pin felled The total score from these throws is: 10 + (3+6) + 3 + 6 +1= 29 A player who scores multiple strikes in succession would score like so: Box 1, ball 1: 10 pins fell (strike) Box 2, ball 1: 10 pins fell (strike) Box 3, ball 1: 4 pins fell Box 3, ball 2: 2 pins fell Box 3, ball 3: 2 pins fell The score from these throws is: Box one... 10 + (10 + 4) = 24 Box two... 10 + (4 + 2) = 16 Box three... 4 + 2 +2 = 8 TOTAL = 48 A player who bowls a strike in the 10th (final) box is awarded two extra balls, so as to allow for their bonus points. If both these balls also result in strikes, a total of 30 points (10 + 10 + 10) is awarded for the box. Spare A "spare" is awarded when all pins are knocked down with a fair ball in or by the second ball roll in the same frame. For example, a player uses the first two balls of a box to clear all ten pins. A player achieving a spare is awarded 10 points, plus a bonus of whatever they score with their next ball (only the first ball is counted). Example: Box 1, ball 1: 7 pins fell Box 1, ball 2: 3 pins fell (spare) Box 2, ball 1: 4 pins fell Box 2, ball 2: 2 pins fell Box 2, ball 3: 1-pin fell The total score from these throws is: 7 + 3 + 4(bonus) + 4 + 2 + 1 = 21 A player who bowls a spare in the 10th (final) box, is awarded one extra ball so as to allow for their bonus points. Ten A Ten (known as "Ten-box") is when all the pins are knocked down after the third ball of a box. A player achieving a Ten is awarded 10 points, but without any bonus for the following ball. Example: Box 1, ball 1: 7 pins felled Box 1, ball 2: 2 pins felled Box 1, ball 3: 1-pin felled The total score from these throws simply is: 7 + 2 + 1 = 10 Calculating scores Correct calculation of bonus points can be a bit tricky, especially when combinations of strikes and spares come in successive boxes. In modern times, however, this has been overcome with automated scoring systems. When a scoring system is "automated", the bowler only has to bowl. It keeps score and will reset the pinsetter after three balls are thrown or all 10 pins have been knocked down. If a scoring system is "semiautomated", the bowler has to enter the score but the computer will keep track of it. The bowler needs to press a button at the end of the ball return to receive a new "rack" of pins. Scoring sheet The candlepin scoring sheet is different from either tenpins or duckpins, in that it is usually oriented vertically, with two columns of squares in a two-square-wide, ten-square-tall arrangement to score one string for one player. The left-hand column is used to detail the "per-box" score, with the cumulative total being recorded down the sheet as each box is rolled in the right-hand column of squares, in a top-down order from the first box to the tenth. Spares and strikes are also marked uniquely in candlepins. Spares are recorded in a box by coloring in the left upper corner of the appropriate left-hand square (using a triangular shape to "fill-in the corner"). If a strike is recorded, opposing corners of the left-hand square are similarly colored in, while leaving sufficient space between the "filled-in" opposing corners, to record the score from the two succeeding balls' "fill" total for the strike. A common (albeit unofficial) practice is to mark a strike on a strike's bonus ball (double strike) by shading in the remaining two corners of the first strike. https://en.wikipedia.org/wiki/Candlepin_bowling