On Monday morning, your friend Jordan walks up to you and says, "I'm thinking of a number between 1 and 100." Being a good sport, you play along and guess 43. "Nope, too low!" Jordan declares. "Fine, how about 82?" you ask. "Too high!" Jordan answers. You keep guessing. 60 is too low. 76 is too high. 70 is too low. Feeling pleased that you are getting closer, you ask, "How about 75?" "You got it!" Jordan replies, and you march triumphantly off to your first class of the day.
But after class, you again run into Jordan, who has apparently been thinking about ways to stump you: why stick to positive numbers? What if you also allow negative numbers? "Now I am thinking of a number between negative 100 and 100," Jordan says gleefully. You decide to take the bait, and you quickly discover that this does not change the game much. You guess, and by going higher and lower you get closer and closer to the target. If Jordan's number is -32, and you have already figured out that -33 is too low and -31 is too high, then you know the answer is -32.

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Go to source: https://kids.frontiersin.org/article/10.3389/frym.2020.00004