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Cards in the card-game Spot-It! include 8 different charms (such as a scissor, a ginger-bread man, a spiderweb, etc.) chosen from a set of 57 different charms. The rules of the card-game of Spot-It! include being presented with two cards from the deck; the winner is the first person to identify the charm that's common between the two cards.

Although the game-play is not so mathematical, and the skills needed to win involve quick observation and focus, the design of the deck of cards leads to investigations of finite projective geometry and the Ray-Chaudhuri–Wilson theorem.

It’s mathematical structure (a finite projective plane of order 7) is discussed in

• https://www.mathteacherscircle.org/assets/legacy/resources/materials/DSenguptaSpotIt.pdf
• http://puzzlewocky.com/games/the-math-of-spot-it/
• in this math.sx question and in this StackOverflow question

In short, each charm corresponds to point on the projective plane, and each card to a line on this plane. Two lines (cards) have exactly one point (charm) in common, which is the basis of the game mechanics.

Cards in the card-game Spot-It! include 8 different charms (such as a scissor, a ginger-bread man, a spiderweb, etc.) chosen from a set of 57 different charms. The rules of the card-game of Spot-It! include being presented with two cards from the deck; the winner is the first person to identify the charm that's common between the two cards.

Although the game-play is not so mathematical, and the skills needed to win involve quick observation and focus, the design of the deck of cards leads to investigations of finite projective geometry and the Ray-Chaudhuri–Wilson theorem.

It’s mathematical structure (a finite projective plane of order 7) is discussed in

• https://www.mathteacherscircle.org/assets/legacy/resources/materials/DSenguptaSpotIt.pdf
• http://puzzlewocky.com/games/the-math-of-spot-it/
• in this math.sx question and in this StackOverflow question

In short, each charm corresponds to point on the projective plane, and each card to a line on this plane. Two lines (cards) have exactly one point (charm) in common, which is the basis of the game mechanics.

See also, this recent (2021) YouTube video from Matt Parker.

Cards in the card-game Spot-It! include 8 different charms (such as a scissor, a ginger-bread man, a spiderweb, etc.) chosen from a set of 57 different charms. The rules of the card-game of Spot-It! include being presented with two cards from the deck; the winner is the first person to identify the charm that's common between the two cards.

Although the game-play is not so mathematical, and the skills needed to win involve quick observation and focus, the design of the deck of cards leads to investigations of finite projective geometry and the Ray-Chaudhuri–Wilson theorem.

It’s mathematical structure (a finite projective plane of order 7) is discussed in

• https://www.mathteacherscircle.org/assets/legacy/resources/materials/DSenguptaSpotIt.pdf
• http://puzzlewocky.com/games/the-math-of-spot-it/
• and in this math.sx question

In short, each charm corresponds to point on the projective plane, and each card to a line on this plane. Two lines (cards) have exactly one point (charm) in common, which is the basis of the game mechanics.

Cards in the card-game Spot-It! include 8 different charms (such as a scissor, a ginger-bread man, a spiderweb, etc.) chosen from a set of 57 different charms. The rules of the card-game of Spot-It! include being presented with two cards from the deck; the winner is the first person to identify the charm that's common between the two cards.

Although the game-play is not so mathematical, and the skills needed to win involve quick observation and focus, the design of the deck of cards leads to investigations of finite projective geometry and the Ray-Chaudhuri–Wilson theorem.

It’s mathematical structure (a finite projective plane of order 7) is discussed in

• https://www.mathteacherscircle.org/assets/legacy/resources/materials/DSenguptaSpotIt.pdf
• http://puzzlewocky.com/games/the-math-of-spot-it/
• in this math.sx question and in this StackOverflow question

In short, each charm corresponds to point on the projective plane, and each card to a line on this plane. Two lines (cards) have exactly one point (charm) in common, which is the basis of the game mechanics.

Cards in the card-game Spot-It! include 6 or so different charms (such as a scissor, a ginger-bread man, a spiderweb, etc.) chosen from a set of 50 different charms. The rules of the card-game of Spot-It! include being presented with two cards from the deck; the winner is the first person to identify the charm that's common between the two cards.

Although the game-play is not so mathematical, and the skills needed to win involve quick observation and focus, the design of the deck of cards leads to investigations of finite projective geometry and the Ray-Chaudhuri–Wilson theorem.

A writeup is in https://www.mathteacherscircle.org/assets/legacy/resources/materials/DSenguptaSpotIt.pdf

Cards in the card-game Spot-It! include 8 different charms (such as a scissor, a ginger-bread man, a spiderweb, etc.) chosen from a set of 57 different charms. The rules of the card-game of Spot-It! include being presented with two cards from the deck; the winner is the first person to identify the charm that's common between the two cards.

Although the game-play is not so mathematical, and the skills needed to win involve quick observation and focus, the design of the deck of cards leads to investigations of finite projective geometry and the Ray-Chaudhuri–Wilson theorem.

It’s mathematical structure (a finite projective plane of order 7) is discussed in

• https://www.mathteacherscircle.org/assets/legacy/resources/materials/DSenguptaSpotIt.pdf
• http://puzzlewocky.com/games/the-math-of-spot-it/
• and in this math.sx question

In short, each charm corresponds to point on the projective plane, and each card to a line on this plane. Two lines (cards) have exactly one point (charm) in common, which is the basis of the game mechanics.