How To Casually Guess Numbers After Dice Throws?

Would it not be pleasing if you could casually guess numbers after dice throws? But hang on a minute! Aren’t dice throws supposed to be random? How would it be possible to guess the numbers beforehand?

Before you make any assumptions, I wish to clarify that we are talking about fair dice here. And no, we will not be bending any properties of randomness to achieve this feat. All you will need is the power of mathematics and a cool head in a party situation to casually impress a clueless crowd.

In this essay, I will first demonstrate this trick once. Next, I will explain the underlying mechanics behind how the trick works. On the one hand, you will be surprised how simple it actually is. On the other hand, it will remain a secret just between you and me. Are you game? Let us begin.

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How I Casually Guess Numbers After Dice Throws?

Let us imagine that you have three dice. Your first task is to roll them once and sum the numbers up in your head (and not reveal them to me yet). While you are doing this, I am not looking at any of the dice or the numbers on top.

Once you have the initial sum, I request you to choose one of the dice and flip it over. You are now to add this number to your sum as well. I’m still not looking at the dice. At this point, I ask you to re-roll the chosen die. Finally, you are to add the number that shows up on top of the re-rolled die to your total as well.

Having missed the critical intermittent steps, now I just take a look at the final configuration and reveal to you the sum you have in your head. You look surprised; I look pleased; there is a smell of mystery in the air.

It might come across as trivial when I explain the scenario in words like this. But you really have to experience this in real life to simply appreciate how satisfying it is. Right, now that you know how the scenario plays out, it is time for me to de-mystify the air around us.

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How Can You Casually Guess Numbers After Dice Throws as Well?

Imagine that you throw the three dice together and get 1, 6, and 4 respectively. You sum these numbers up to 11. Let us say that you choose the die showing 4 at this point. You flip this die over and add that number to your sum as well. Now, you re-roll this die and get 2. Finally, I get to see the following configuration (note that this is the first time I’m seeing the dice):

Now, I look at you dead in the eyes and nonchalantly say:

“The sum you have in your head is 16.”

How was I able to tell that without knowing the intermittent steps? Well, there is a sly trick I pulled off here. You see, the result of a fair die-throw is indeed random; there are no questions about that. What I am actually taking advantage of here is the deterministic way in which dice are designed.

If you were perceptive, you would have noticed that the only variables I missed were the number on the top side of the die you chose and the number on its flip side. Here’s where the typical die’s construction comes in. Cubical dice are designed such that opposite numbers always sum up to 7 (1–6, 2–5, and 4–3).

Since I know this fact beforehand, I use it to my advantage by tricking you into thinking that I have missed the crucial intermittent steps. However, in reality, I just take a look at the final configuration, sum up the numbers and add 7 to the total before I tell it to you.

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Final Thoughts

There is one more thing that you need to note though. In order to come across as if you are pulling off a magic trick, you will need to practice summing up numbers quickly in your head. If it helps in any way, one of the four numbers will always be a 7. The remaining three numbers would not be greater than 6.

Once you are comfortable with this process, you may choose to venture even further and ask your participant to flip two dice instead of 1. Now, you have the added challenge of adding 14 instead of 7. But other than that, the process remains the same. Plus, the feat comes across as even more impressive. You may even increase the total number of the dice; it is entirely upto you.

Now that I have shared how this little trick works with you, make sure that this remains a secret just between you and me. I wish you loads of fun showing off this trick to impress your clueless friends!

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Reference and credit: Martin Gardener.

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Further reading that might interest you: How To Use Science To Win At Rock-Paper-Scissors? and How To Actually Subtract Using Addition?

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