Can You Solve My Problems?: Ingenious, Perplexing, and Totally Satisfying Math and Logic Puzzles by Alex Bellos

Author:Alex Bellos [Bellos, Alex]
Language: eng
Format: azw3
Publisher: The Experiment
Published: 2017-04-17T16:00:00+00:00

ANSWERS

Ten tasty teasers

Are you smarter than an 11-year-old?

1) D

The three images show that there are six letters on the cube: I, K, M, O, U, and P. Since a cube has six faces, these must be the only letters on the cube. The first view of the cube shows that I and M each share a side with K. The second view shows that O and U each share a side with K. Only four faces can share a side with K. If the cube is positioned such that K is on the top, as in the first image, then I is adjacent in a clockwise direction from M. We can deduce from the second image that when K is on the top the O is adjacent in a clockwise direction from U, so the clockwise order of faces around K must be M-I-U-O. Thus M is opposite U.

2) D

After nine lies, the length of his nose will be 29 × 5cm = 512 × 5cm = 25.6m. This is close to the length of a tennis court, which is 23.8m. This distance is well short of the physical maximum for Pinocchio’s nose, however, according to a 2014 report from the University of Leicester’s Centre for Interdisciplinary Science. According to its calculations, if the puppet’s wooden head is 4.18kg, with a 6g nose of initial length one inch (2.54cm), the nose will break only after 13 fibs, when it reaches a length of 208m.

3) C

Eighteen has eight letters and is not a multiple of 8.

4) D

Well, for starters Amy is to the left of both Ben and Chris. So the three are in the order Amy, Ben, Chris, or Amy, Chris, Ben. That’s all we know, so D is certainly true. None of the other statements must be true, even though B may be true.

5) E

You could find this out by trial and error. Or maybe you worked out the rule: For it to be possible to draw a figure without taking the pen off the paper and without drawing along an existing line, there must be at most two points in the figure at which an odd number of lines meet. Only E satisfies this condition.

6) B

I hope at least that you know your seven times table! If you do it will come as no surprise that 7 divides 35, so 7 divides 350,000. Seven also divides 49, so 7 divides 4,900. Since 354,972 = 350,000 + 4,900 + 72, we are left to find the remainder of 72 divided by 7. Since 7 × 10 = 70, the remainder is 2.

7) C

There must be at least two boys, because if there was only one boy he would have no brother, which contradicts the question. Likewise, there must be at least two girls, so the smallest number is four.

8) E

Just do this fun multiplication on the back of an envelope and be done with it.

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