Coin flip: heads or tails

1. Tap the coin, or press Space. It spins and lands on heads or tails.
2. To settle a choice between two people, pick Best of 3 or Best of 5, and give each side a name.
3. The first side to win 2 flips, or 3 in a best of 5, wins the match.
4. Press Copy link or Share to send the result. The link shows the same flips.

Each flip is a new 50/50: the coin has no memory, so after 4 heads in a row, heads is still exactly as likely as tails. Over many flips, heads comes close to half of them, but rarely exactly half.

Streaks are more common than most people think. In 30 flips, a run of 4 or more of the same side shows up about 9 times in 10, and a run of 5 or more about 6 times in 10. The chance that the next 5 flips are all heads is 1 in 32, and for 10 flips, 1 in 1,024.

• Pick who goes first in a game, or who picks the film.
• Settle a tie between two choices, like pizza or tacos.
• Teach probability: flip 30 times and count the heads. You get close to 15, and exactly 15 about 1 time in 7.

Need more than two sides? Roll the dice roller, or spin the yes or no wheel.