Plinko

Where to drop, and why the middle is not a sure thing

Plinko is gloriously simple: choose a spot along the top, release the ball, and watch it clatter down through the pegs into a scoring slot. Every peg is a tiny coin flip, so no two drops trace the same path even from an identical starting point. That randomness is the whole appeal, and the reason there is no perfect strategy, only better odds.

Here is the counterintuitive bit. A centre drop does not guarantee a centre landing, yet across many balls the pegs steer results toward the middle far more often than the edges. Countless wobbly routes end up somewhere near the centre, and very few stay pinned to one side the whole way down.

• You get a fixed number of balls, so treat the game as building a total rather than chasing one huge drop.
• Match your drop point to where the points are: aim over the high slots, but expect the ball to wander a column or two either way.
• Make peace with the bounces you cannot control; half the fun is the ball taking a wild carom into a slot you never aimed at.

With a fixed number of balls, think in totals. If the highest slots sit in the centre, drop centre every time and let the spread work for you. If the layout puts big points at the edges, accept that you are buying a long shot: drop as close to the target edge as you can, since the wall folds some stray bounces back toward it, and count on one or two balls straying true rather than all of them.

Count the paths

Here is the neat bit of maths under the board. Treat every peg as a coin flip, left or right. On a small board four pegs deep, a ball has sixteen possible routes: only one hugs the far left the whole way down, four reach the next slot in, and six land in the middle. Those counts, 1, 4, 6, 4, 1, are a row of Pascal's triangle, and they are why the centre fills up. The board does not pull balls anywhere; the middle simply owns more of the possible routes. On a full-size board the same arithmetic just gets steeper, and the rare edge-to-edge run becomes the story you remember precisely because the counting is against it. Sixteen routes fit in your head; a real board's thousands do not, but they obey the same triangle.

One honest warning from the same maths: the board has no memory. Every drop is independent, so three balls drifting left in a row say nothing about ball four. Moving your aim to chase a pattern in past bounces is superstition. Move it only because the slot values make a different target worth the attempt.

The Price Is Right made it famous

Plinko is best known as the marquee pricing game on the American television show The Price Is Right, where it debuted in January 1983. Frank Wayne, the show's executive producer, is credited with creating it, and four decades on it is still the game contestants most visibly lose their minds over: earn some chips, climb to the top of the big board, and let the studio hold its breath through every clatter. The name has since become the generic word for any peg-board drop game, which is why versions of it turn up at fairs, in arcades, and here.

A physics demo in disguise

The board itself is older than television. It is essentially a Galton board, the device the Victorian scientist Francis Galton built in the 1870s to show how many small random knocks add up to a bell curve. Drop enough balls and the slots fill into that famous humped shape, tall in the middle and thin at the edges, a live demonstration of what statisticians call the central limit theorem. Galton used lead shot behind glass; you are using a ball and a score counter, but the experiment is identical. Knowing the maths does not make the drop any less fun. If anything it sweetens the freak results: when a ball does ride the wall all the way into a corner slot, you know exactly how unlikely the thing you just watched was.