Parlays are fun for the same reason lottery tickets are fun. You put down a little, you probably lose it, and once in a while you win big. Nothing is wrong with paying for that fun. It just helps to know the price, the same way a lottery ticket prints the odds on the back.

This guide puts both on one scale: how much of every dollar you get back, on average, over many tries.

US lotteries pay out roughly half to two-thirds of the money they take in as prizes. The exact share depends on the state and the game. So a $1 ticket gives back somewhere around 50 to 65 cents on average, and the other 35 to 50 cents goes to the state and the lottery's costs.

The chance of the biggest prize is tiny. The Powerball jackpot is 1 in 292.2 million. Most of the money people win comes from small prizes.

A single bet at -110 on a fair coin-flip game gives back about 95.5 cents of every dollar on average. The other 4.5 cents is the bookmaker's cut. A parlay charges that cut once for every leg, so the share you get back shrinks with each leg you add.

Each line is the chance of one leg multiplied by itself, and the 95.5 cents multiplied by itself, once per leg. You can check any of them with a calculator.

Somewhere around eight to ten legs, a parlay gives back about what a lottery ticket does. A short parlay is a much better price: two or three legs give back 87 to 91 cents of every dollar, nowhere near a lottery's 50 to 65.

Same-game parlays and boosted long shots can cost more than these coin-flip numbers, because the sportsbook sets those payouts its own way. That is why it pays to check the actual payout you are offered.

A lottery ticket never pretends to be skill. A parlay often does. When a tout sells a "five-leg lock," the pitch is that knowing sports beats the math. Each extra leg mostly adds another cut. Knowing the teams well can move a single pick a little, but it cannot undo a cut charged five times.

For entertainment and education. Nothing here predicts results or recommends a bet.