Science shows you how to win at rock, paper, scissors. Every time.

Are you in the habit of suggesting a round of rock, paper, scissor to resolve fights over who gets the last Tim Tam?

Yeah, us too.

Lucky for us, science is on our side — because an actual formula has been revealed that shows how to win at the game every single time.

The answer? Calculated strategy.

The basic concept goes like this:

“If a player wins over her opponent in one play, her probability of repeating the same action in the next play is considerably higher than her probabilities of shifting actions.”

In other words, a winner will tend to play the hand they last played to win, and a loser will usually change their hand to the one they were defeated by.

These results, which are bound to change the face of pre-school playgrounds as we know them, are all thanks to a social experiment conducted by three Chinese scientists.

By splitting 360 students into groups of six and observing them as they played several rounds of the game, the scientists were able to find certain patterns. But to keep the player’s attention (they did have to play 300 times), they each got a bit of money after every round.

Here’s an example game:

Say “Hi” to Bob and Betty. Bob plays scissors and Betty plays paper. Bob wins. Thanks to his glowing ego after that glorious victory, Bob will proceed to play scissors with his next opponent, while Betty will abandon her previous strategy and mostly likely also opt for scissors against her new partner.

So next time you’re faced with a conundrum and fists are about to shake, know that your victory will depend on more than random chance. You just need to know your opponent’s last move.

You got this. Go forth and win that last Tim Tam!

Editor’s note: You guys, we need your help to settle an office argument. Is it ‘paper, scissors, rock’, ‘rock, paper, scissors’ or ‘scissors, paper, rock’?