One of the first things computer engineers learn is digital logic and the most fundamental is switching theory.    

Wide Clyde is alone in the basement in his summer house deep in the woods away from civilization.  He wants to go upstairs to cook some Top Ramen noodles. To do that, he needs to identify which of three switches controls the hot plate upstairs. The hot plate is plugged in but currently off. The other two switches turn outside lights off and on. Wide Clyde can’t see outside, so he can’t determine which switches control the lights.  He only wants to make one trip upstairs to determine which is the hot plate switch. How can he do it?

We’ll give the answer to this Micro Softy next week. 

Solution to Micro Softy 66: Reducing Repetitive Repetition    

Here’s last week’s Micro Softy. 

 Choose any three-digit number, say 567, and repeat it: 567,567. Divide it by 13, then 11 and then 7. The result will be the original number, 567. This works for any three-digit number. Why? 

Here’s the answer. Any three-digit number multiplied by 1001 duplicates the number. For example, 214 x 1001 = 214,214. And 13 x 11 x 7 = 1001. So dividing the big number by 13, then 11 and then 7 is the same as dividing by 1001. The original three-digit number always results! 

Deeper insight for nerds: This also happens in base 2 where 1001 corresponds to 9 in base ten which is 3×3. Multiply, in binary, the three-bit number 110 (6 in base ten) by 1001 and you get 110,110 (54 in base 9). Dividing by 54 by 3 twice gives 6. This is 110 in base 2 which was the original number. 

The method works for all bases. The only thing that changes is what 1001 means. In base three, for example, 1001 is 28 = 2x2x7. As an example, 120 in base three is 15 in base ten. Divide 120,120 in base three by 4 and then by 7 and you get 120 (15 in base 10) back in base three. 

Pretty slick, eh? 

The Monday Micro Softy is a weekly feature of Mind Matters News. Here are the links to all the puzzles and answers to date:

Monday Micro Softy 66: Reducing Repetitive Repetition requires being BFF’s with numbers, and last week’s Micro Softy was tough and mathy. Here is the solution: Any three-digit number multiplied by 1001 duplicates the number. For example, 214 x 1001 = 214,214. And 13 x 11 x 7 = 1001. So dividing the big number by 13, then 11 and then 7 is the same as dividing by 1001. The original three-digit number always results! 

Monday Micro Softy 65: Fathers and sons was about two fathers and their two sons who walked into a Bass Pro Shop in Memphis, Tennessee. Each man bought an AK47 rifle with ammunition and a 75-round drum magazine. But all together, only three AK47’s were sold. How could this be? The solution is there were altogether two fathers (father and grandfather) and two sons (the father and his son) but only three men. You can find puzzles 55 through 65 here as well.

Monday Micro Softy 64: Old Time Phishing was about an investment banker, Geardown Geko, who received anonymous tips forecasting the outcome of future events starting in 1948. The solution is: The winner of Tipper’s phishing lottery. It was a type of phishing where in the end there was a single winner participant, Geko. Someone had to win. Everyone else who bet on the predictions eventually was a loser. You can find puzzles 55 through 64 here as well.

Monday Micro Softy 63: A Beggar’s Tale. Exceptional nerds are psychologists who see through surface actions. Such a skill is required to solve this Micro Softy. The solution to Freaky Bob’s strategy is: If he had taken the $10, he’d have lost repeat customers. Nobody would’ve been entertained. Choosing the $5 kept people coming back with more cash, proving far more lucrative for him in the long run. You can find puzzles 55 through 63 here as well.

Monday Micro Softy 62: The Ordeal of Sisyphus Fats. The best computer programmers and engineers must be good at scheduling. Last week’s Micro Softy tests this ability and the solution is that Sisyphus Fats took 98 minutes to push the large bowing ball to the top of the 100-foot hill. You can find puzzles 55 through 62 here as well.

Monday Micro Softy 61: Micro Softy Take Five was more of a trivia question than it was a puzzle. To solve Micro Softy 61, the answer is the theme for the Mission Impossible movie franchise starring Tom Cruz. You can find puzzles 55 through 61 here as well.

Monday Micro Softy 60: Here’s a puzzle from Gunsmoke Told to “get out of Dodge”after a shooting, a gunslinger does so at a nearly inexplicable time. Can you solve the puzzle?
To solve Microsofty 59, recall that direction of air flow is due to pressure — not size. Which tire is under more pressure? You can find puzzles 56 through 59 here as well.

Monday Micro Softy 55: “It happens every spring.” Baseball, that is. Here’s a puzzle that takes in baseball’s summer. To solve last week’s puzzle, you don’t need to know the distance. Check the problem again for the number you do need to know. You can find puzzles 51 through 54 here as well.

Monday Micro Softy 50: Cutting through the cornbread. How did Yuri Senior cut the cornbread into eight identical portions using only three straight cuts? You can guess the answer to Microsofty 49 if you try the test question yourself at home, using a small mirror. Links to Microsofties 46 through 49 are here as well.

Monday Micro Softy 45: Can Tony beat the fast-food curfew? An early curfew on fast food service motivated a boy to exercise more vigorously. But how fast was he pedaling? To solve Micro Softy 44, recall that Tony doesn’t need to take the individual pills each day, only the prescribed amount of each. You will find links here to Micros Softies 41 through 44 as well.

Monday Micro Softy 40: The fate of a false prophet. He wasn’t actually fired for being a false prophet but for something that his prophecy unintentionally revealed. The solution to Micro Softy 39 lies in considering an alternative possible meaning of a word commonly used in sports. You will also find links to Micro Softies 30 through 39 and their answers here as well.

Monday Micro Softy 29: A funeral lament in four lines. The funeral director was puzzled by Dan’s description of his relationship to the deceased but there was no question that his grief was sincere Here, you will also find links to Microsofties 22 through 29.

Monday Micro Softy 21: Finding More of the Deadly Fentanyl Pills. Here, you will also find links to Microsofties 11 through 20 as well.

Monday Micro Softy 11: What Happened to That Other Dollar? Here you will find links to the first ten Micro Softies. Have fun!