A teacher writes six words on a board: "cat dog has max dim tag." She gives three students, Albert, Bernard and Cheryl each a piece of paper with one letter from one of the words. Then she asks, "Albert, do you know the word?" Albert immediately replies yes. She asks, "Bernard, do you know the word?" He thinks for a moment and replies, "Yes." Then, she asks Cheryl the same question. She thinks and then replies, "Yes." What is the word?

Answer: Dog. Albert knows right away because he has one of the unique letters that only appear once in all the words: c o h s x i. So, we know the word is not "tag." All of these unique letters appear in different words, except for "h" and "s" in "has," and Bernard can figure out what the word is from the unique letters that are left: t, g, h, s. This eliminates "max" and "dim." Cheryl can then narrow it down the same way. Because there is only one unique letter left, the letter "d," the word must be "dog." (For more on this answer, watch the video below.)

23. Logic Puzzle: You have five boxes in a row numbered 1 to 5, in which a cat is hiding. Every night, he jumps to an adjacent box, and every morning, you have one chance to open a box to find him. How do you win this game of hide and seek?

Answer: Check boxes 2, 3 and 4 in order until you find him. Here's why: He's either in an odd or even-numbered box. If he's in an even box (box 2 or 4) and you check box 2 and he's there, great; if not, you know he was in box 4, which means the next night he will move to box 3 or 5.

The next morning, check box 3; if he's not there, that means he was in box 5, and so the next night he'll be in box 4, and you've got him. If he was in an odd-numbered box to begin with (1, 3, or 5), though, you might not find him in that first round of checking boxes 2, 3 and 4. But if this is the case, you know that on the fourth night, he'll have to be in an even-numbered box (because he switches every night: odd, even, odd, even), so then you can start the process again as described above. This means if you check boxes 2, 3 and 4 in that order, you will find him within two rounds (one round of 2, 3, 4; followed by another round of 2, 3, 4). For more on this answer, watch the video below.

24. Logic Puzzle: The "Monty Hall" problem was made famous when it appeared in Parade magazine's "Ask Marilyn" column in 1990, and it was so counterintuitive it had everyone from high school students to top mathematical minds questioning the answer—but rest assured

Question

A teacher writes six words on a board: "cat dog has max dim tag." She gives three students, Albert, Bernard and Cheryl each a piece of paper with one letter from one of the words. Then she asks, "Albert, do you know the word?" Albert immediately replies yes. She asks, "Bernard, do you know the word?" He thinks for a moment and replies, "Yes." Then, she asks Cheryl the same question. She thinks and then replies, "Yes." What is the word?

Answer: Dog. Albert knows right away because he has one of the unique letters that only appear once in all the words: c o h s x i. So, we know the word is not "tag." All of these unique letters appear in different words, except for "h" and "s" in "has," and Bernard can figure out what the word is from the unique letters that are left: t, g, h, s. This eliminates "max" and "dim." Cheryl can then narrow it down the same way. Because there is only one unique letter left, the letter "d," the word must be "dog." (For more on this answer, watch the video below.)

23. Logic Puzzle: You have five boxes in a row numbered 1 to 5, in which a cat is hiding. Every night, he jumps to an adjacent box, and every morning, you have one chance to open a box to find him. How do you win this game of hide and seek?

Answer: Check boxes 2, 3 and 4 in order until you find him. Here's why: He's either in an odd or even-numbered box. If he's in an even box (box 2 or 4) and you check box 2 and he's there, great; if not, you know he was in box 4, which means the next night he will move to box 3 or 5.

The next morning, check box 3; if he's not there, that means he was in box 5, and so the next night he'll be in box 4, and you've got him. If he was in an odd-numbered box to begin with (1, 3, or 5), though, you might not find him in that first round of checking boxes 2, 3 and 4. But if this is the case, you know that on the fourth night, he'll have to be in an even-numbered box (because he switches every night: odd, even, odd, even), so then you can start the process again as described above. This means if you check boxes 2, 3 and 4 in that order, you will find him within two rounds (one round of 2, 3, 4; followed by another round of  2, 3, 4). For more on this answer, watch the video below.

24. Logic Puzzle: The "Monty Hall" problem was made famous when it appeared in Parade magazine's "Ask Marilyn" column in 1990, and it was so counterintuitive it had everyone from high school students to top mathematical minds questioning the answer—but rest assured