"What do you think?" asked the scholar Surrates, looking at Richard.

Richard's gaze retracted from the title of the papyrus scroll, and his eyes flashed, "Twenty-two days." ”

"Huh?" said Suradies, a scholar, "what 22 days?"

"If you solve this question in the right way, it will take up to 22 days for Sulla, an imposter of universities, to find the thief Raddie hiding in the secret room. Richard said.

Suradies looked at Richard for a few seconds, then groaned, and then nodded appreciatively: "Well, yes, it's very consistent with my previous guess, yes, it's 22 days." Come on boy, tell me about your thinking, and let me see if you think differently or wrong than I do. ”

"Think of it this way, and number all thirteen houses – from No. 1 to No. 13. In the question, the thief Lardy changes the room, either from even to odd - for example, from room 1 to room 2, or from odd to even - from room 1 to room 2.

In this way, we assume two scenarios: on the first day, the thief Lardy is in an even-numbered room, or on the first day, the thief Lardy is in an odd-numbered room.

If Lardy the Thief is in the even-numbered room on the first day, then we search Room 2 on the first day, Room 3 on the second day, Room 4 on the third day, and until the eleventh day we search for Room 12, the thief Ratch will most likely be found in the process. Because the distance between Sura, the impostor who searched the room, and Raddie, the thief, would definitely be an even number - either 0 or a multiple of 2. When the distance is 0, it means that the search is successful and the thief Raddy is caught.

And if the thief is not found in the end, then it means that the thief Laddy stayed in the odd room on the first day. Then on the next day, the twelfth day, he will definitely stay in the even-numbered room. In this way, the impostor Sula can go back and continue the search from room 2, and the worst-case scenario is to catch the thief Laddy in room 12 on the 22nd day and retrieve the stolen treasure. ”

"Hmm......" After listening to Richard's words, the scholar Suradis pondered for a long time, then looked at Richard and nodded, "Well, yes, your thinking is very correct, almost exactly the same as mine." You...... Well, wait a minute, I'll write a draft of the reply to that old bastard of Naathod. ”

After saying that, the scholar Suradies picked up a quill pen, opened a new papyrus scroll, and began to "brush and brush" to write.

Half a ring, almost written, Surrates looked at the contents, fell into deep thought again, and said to Richard: "Athode deliberately made a difficult problem for me, although ...... Ahem, it didn't really make me feel embarrassed, but I should have responded to him with a similar problem.

There are a couple of difficult questions that come to mind, but none of them are quite suitable. Do you have a suitable question, preferably one that is very difficult to solve......"

"Forehead......" Richard's eyes flashed, and thoughts raced.

There were too many of them, and one of them he had always wanted to know was what was the truth of this world, and what was the nature of time travel?

In addition, a long time ago, the spirit of the "Monroe Chapter" book spirit, resulting in several problems that the book spirit has not responded to so far, are also counted - the grand unified theory, the Riemann conjecture, and the accurate value of pi.

However, considering these questions, he also can't give answers, so it's better to replace them with a few simple points. Like what...... Poincaré's conjecture, which is one of the seven major mathematical problems of the modern earth world and has been successfully solved, is the same as the Riemann conjecture:

Any single-connected, closed three-dimensional manifold is homeomorphic to a three-dimensional spherical surface.

To put it simply, every closed three-dimensional object without a hole is topologically equivalent to a three-dimensional sphere.

To put it simply, if an apple (or other spherical fruit) is tied to the surface of a rubber band, try to stretch it, neither tear it off nor let it off the surface, let it slowly move and shrink to a point, but tie the rubber band to the surface of a tire in an appropriate way, without pulling the rubber band, there is no way to shrink the rubber band to a point without pulling the rubber band. As a result, the surface of the apple is "single-connected", but the surface of the tire is not.

Richard was about to speak, but stopped when he said something, because it suddenly occurred to him that something about topology might be a little too challenging for the thinking of the scholar Suradis in front of him. If he really said it, he would probably need to popularize the definitions of three-dimensional, manifold, and embryo first.

So...... Let's try to make it simpler, preferably a simple numerical problem—a "hard work problem" that has no technical content, but requires a lot of calculations to complete.

So......

"Think so. Richard looked at Sulrates and spoke, "Among the numbers, there is a special existence, such as 121, 363, etc., they read from left to right, and they read from right to left, which is the same, and this kind of number can be called palindrome number. And these numbers are not unfounded, it can be split into many other numbers.

For example, if you add the number 56 to the number 65 in reverse order, you get the palindrome number 121.

For example, adding the number 57 to his inverse number, 75, gives us 132. 132 is not a palindrome number, but if you add it to his other inverse number, 231, you get the palindrome number of 363.

For example, add 95 to the number 59 to get 154. Add 154 to 451 to get 605. Add 605 to 506 to get 1111 - after three iterations is another palindrome number.

In fact, about 90% of the numbers within 100 can get a palindrome number within seven iterations, and about 80% can get a palindrome number within four iterations.

Of course, there are also those with a large number of iterations, such as 89, which requires 24 iterations to get the 13-bit palindrome number of 8,813,200,023,188.

After 100, such as the number 10,911, it takes 55 iterations to get the 28-bit palindrome number—4,668,731,596,684,224,866,951,378,664.

A super large number like 1,186,060,307,891,929,990 takes 261 iterations to get a qualified palindrome, and the result has exceeded 100 bits, reaching 119 bits.

So does there exist such a number, and no matter how many iterations it goes through, it can't come up with a palindrome number? We can call it a Lickrell number, and if it really exists, what is the minimum?"

"......" The scholar Surates was silent, silent for a long time, looked at Richard, silently walked to the side of the desk, picked up the tea that had been brewed at some point and had been cold for a long time, and took a sip.

After drinking tea, the scholar Sauradies looked at Richard, nodded first, and agreed: "Well, it's a good topic." ”

Then two questions were asked—two very serious questions.