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Coin flipping

math Maturity 7-9 Next article →

Have you ever had to make a choice between two things? Sometimes, deciding is hard because both options seem just as good. A coin flip is a simple way to choose fairly.

Coin Toss (3635981474)
Coin Toss (3635981474)

You use your thumb to launch a coin into the air. The coin spins many times in an unpredictable way. Before it lands, you call out "heads" or "tails." The other person takes the opposite side. When the coin stops, the person who called correctly wins. This method is a form of sortition, which means picking by chance. It is a very fair way to settle a dispute.

There are many ways the coin might land. Usually, it lands on one of its two flat sides. However, it is possible for a coin to land on its edge. This can happen if it hits an object like a shoe. For an American nickel, this happens about 1 in 6,000 times.

1970 Anglo-Italian Cup - Juventus v Sheffield Weds - Coin toss
1970 Anglo-Italian Cup - Juventus v Sheffield Weds - Coin toss

Scientists even study the thickness of coins to understand this. They look at the ratio of a coin's thickness to its diameter. This ratio is thought to be between 0.577 and 0.866. Some people even use three coins to pick between three choices. This three-way flip works about 75% of the time.

penney game graphs
penney game graphs

People have used coins to make decisions for a very long time. The Romans had their own way of doing this. They called it "navia aut caput," which means "ship or head." This was because their coins showed a ship on one side and an emperor's head on the other.

Pompey by Nasidius
Pompey by Nasidius

In England, people used the terms "cross and pile." Even in the United States, a coin helped name a city. Two men wanted to name a new town after different places. Francis W. Pettygrove won the choice with a coin flip. The coin he used is now called the Portland Penny.

Sports use coin tosses all over the world to be fair. In American football, a toss decides which team gets the ball first. The NFL even uses specially made coins for their games.

In cricket, the captain uses the toss to decide whether to bat or bowl. This choice can change how the whole game goes.

BradmanAllenToss
BradmanAllenToss

Tennis players also use a toss to see who serves first. In association football, the winner chooses which goal to attack. Even in the 1968 European Championship, a coin toss helped decide a match between Italy and the Soviet Union. Italy won that match and became the champions.

Coin flipping is about more than just winning a game. It represents the idea of equal opportunity for everyone. When people cannot agree, a coin toss shows they are being fair. It helps prevent arguments from turning into bigger struggles. This happens in business and even in politics. In Canada, a coin flip once decided a project for painting city streets. In the Philippines, a coin can help break a tie in an election. It is a way to find an answer that everyone can accept. Even scientists use it to decide the order of names on a paper.

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🖼️ Images & Media (6)
File:Coin Toss (3635981474).jpg
Coin Toss (3635981474).jpg
File:Pompey by Nasidius.jpg
Pompey by Nasidius.jpg
File:Coin toss at Super Bowl 43 1.jpg
Coin toss at Super Bowl 43 1.jpg
File:1970 Anglo-Italian Cup - Juventus v Sheffield Weds - Coin toss.jpg
1970 Anglo-Italian Cup - Juventus v...
File:BradmanAllenToss.jpg
BradmanAllenToss.jpg
File:penney_game_graphs.svg
penney_game_graphs.svg
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