An apartment building on the Upper East Side in Manhattan, New York, USA

"Since the 11 people in front of you have pressed the buttons from the 2nd floor to the 5th floor, why haven't they passed the guò assessment?" 20 years ago, John Leto, an undergraduate student at Columbia University's College of Arts and Sciences, used all his brains to analyze the difficult situation he was facing, and soon he thought that the order of the buttons on the elevator was the key to determining whether he could pass the guò assessment, and once he pressed the wrong button, I am afraid that there would be no second chance, and from the fingerprint observation of the spray, the previous 11 candidates chose 2 and 5 The two buttons have the most fingerprints, the second choice of 3, and the least choice of 4......

"Is it 2 or 5? Or rather, press nothing? Is there any way to keep yourself in this apartment instead of walking away from the fire staircase with a $20 fare if you can't find your target within 5 minutes, as the janitor boss said? Compared to the $10,000 retainer, the $20 paper bill is a joke! John Leto circled around the elevator like a sleepy beast, all but his own chaotic footsteps, all other external sounds seemed to freeze and become silent.

John Leto looked at his watch, the time to enter the elevator has passed 2 minutes, and he is still stuck on the elevator button and does not know how to choose, perhaps, not to make a choice is the best choice? As a former senior tax commissioner of the Internal Revenue Service, John Leto also had his own glory days, his brain was good when he was not drinking, and his education experience in the Department of Modern Information Management at Columbia University's College of Arts and Sciences allowed him to make the most accurate judgments and choices in the face of a complex information environment.

"$20 bill?" John Leto's hand unconsciously touched the $20 paper note given by the head of the gatekeeper who was in his pocket, and involuntarily touched the paper bill and held it up to look at it seriously, it was just a half-new green dollar bill with a little wrinkle, in the economic life of American society, the frequency of use of $20 paper money is second only to $5 and $1, as for the $100 paper bill is usually rarely used in circulation, too ostentatious and easy to attract attention.

"$20, 20, means button 2 might be the best choice?" John Leto's hand reached for button 2, but hesitated to know whether to press it or not, the head of the person on the $20 banknote is Andrew Jackson, the seventh president of the United States, the presidency was from 1829 to 1837, as the first president of the Democratic Party, Andrew Jackson's existence caused the American Civil War to be artificially delayed for 30 years, John Leto, a recipient of a bachelor's degree from a liberal arts college, is familiar with this period of American history......

In fact, Andrew Jackson was born on March 15, 1767, died on June 8, 1845, and served two consecutive terms as president and reigned for eight years. John Leto felt a sweat in the palm of his hand, as if he had touched a little eyebrow but seemed to be ignorant and couldn't find the direction at all, this is a five-story apartment, just across from Park Avenue, there are only 12345 and a total of 12345 keys to select the floor and the emergency button to open and close the door, which is a bit unreliable with the seventh president's two consecutive 8-year terms and the year of his birth and death?

5 minutes? Isn't 5 minutes also a hint? John Leto's ears rang with the look and smile of the janitor when he handed him $20, of course, the other party's grin can also be seen as a smile, the $20 note must contain some additional information, of course the bill has a serial number, but it looks like a long list of numbers...... Wait a minute...... Banknotes - serial numbers on the bill?!

John Leto held the $20 note in his hand above his head, looked carefully at the number on the note in his hand in the light, and EB52212124BB2, is it the order of the elevator buttons?! The serial number on the banknote does not exceed 5, which is exactly the number that can be pressed with the numbers on the elevator button...... It must be so, it must be so, the countdown of the digital electronic watch on his wrist - the timer is less than 30 seconds, John Leto took a deep breath, stretched out his hand to the button area of the elevator, and quickly pressed the 522121242 of the string of numbers, now the four buttons of 1245 are lit up, and the elevator begins to rise slowly......

Unlike ordinary elevators, this obviously debugged and modified elevator does not show the rising floor, and when the elevator stops, John Leto can't even confirm which floor the elevator is on, but surprisingly, after the elevator stops, it is not the elevator door that came in at the beginning that opens, but the hidden elevator door behind John Leto, outside the door is a circular corridor, and a printed piece of paper is pasted on the wall, "Congratulations on entering the second level!" The second level costs $100, so find a new target on this level! Underneath the slip of paper was a beautiful brand new $100 note!

John Leto couldn't believe his eyes, Nima really made himself rush through the first level by mistake for a long time, no one will know, this elevator will open before and after, I'm afraid everyone won't press the button like themselves, the guy who came up with this way to test people is definitely a perverted guy to the extreme, fortunately, the $20 car and horse fare was not taken in vain, this is considered to enter the second level? And a $100 reward?!

John Leto walked out of the elevator almost with a little tune, and looked left and right, and there were closed doors on both sides of the long corridor, about 40 of them, and there were no windows in the corridor, and I don't know which floor it was on, but since it was past the first level. Since the brand new $100 note was not taken by the guy who applied earlier, he may now be the only candidate who has a chance to win the grand prize of 10,000 yuan......

John Leto carefully took off the $100 sticker stuck to the prompt paper, thought about it, looked left and right to see that there was no one else, the light in the corridor was not bright or dark, it looked like the executive floor of some four-star hotel, the floor was covered with valuable carpets, the corridor was on both sides of the door, the door was a four-digit number, the door actually used a numeric keypad lock, it seems that the right door is selected, and enter the correct door opening code, in order to pass the second level of the guò test......

Fortunately, there is no time limit this time, but John Leto still set the time for the digital watch, with the stopwatch beating, he carefully observed the $100 paper in his hand by the light for a while, subconsciously hoping that the $100 paper bill is the key to open the second level, but he felt that the person who asked the question would not let himself pass the level so easily, for the sake of insurance, John Leto took off the paper that prompted him to pass the first level from the wall.

After looking at it for a long time, there was no more information and hints on the notice paper, and the former IRS tax investigator leaned on the wall and looked at it carefully for a long time, and finally found nothing, and finally, he put the note and the $100 paper bill into his pocket, and began to walk down the corridor with the briefcase, and in a few minutes, he walked from this end of the corridor to the bottom, 20 rooms on the left and right, the doors were closed, and the porch at the bottom of the corridor was locked. Looking at the situation, there is a fire escape downstairs outside, but the curtains are all down, so it is impossible to judge the floor that appears on......

There are a total of 40 rooms on this floor, and the numbers on the door are all 17, but it is not from 1701 to 1749, of course it will not be the 17th floor, it can be seen that the digital electronic door lock of each room is the original device, but the number on the door is temporarily pasted, John Leto randomly picked a door with a 1717 number printed in the middle of the corridor, and boldly reached out to try to uncover the number plate pasted on it, but the double-sided tape seemed to be a little tight, and it was torn for a long time and did not open it. I had to give up this plan......

In order to save his body, John Leto sat down in the middle of the corridor, gasped for a while, simply opened the briefcase he brought, took out the cold hot dog that he bought at the hot dog stall at the exit of the subway station in the morning, and ate it, and did not forget to take out a can of Coke and open it and drink it, rested for 10 minutes, and after destroying a can of Coke and a cold hamburger, John Leto recovered a lot of body and spirit, and put the wrapper and Coke cans back into the briefcase......

John Leto took out the $100 note and looked at it again, the figure on the $100 note was Benjamin Franklin, an inventor and printer who was not president, but the most famous and high-ranking figure in American history, Benjamin Franklin (Benjamin Franklin) was an 18th-century American industrialist, scientist, social activist, thinker, writer and diplomat.

Franklin was the first scientist and inventor in American history to achieve international fame. In order to explore electricity, he once made the famous "kite real yàn", which has made remarkable achievements in electricity, and in order to deeply explore the laws of electrical motion, many special nouns such as positive electricity, negative electricity, conductive body, battery, charge, discharge, etc. have become universal words in the world. He borrowed the mathematical concept of positive and negative, and the first scientifically used the concept of positive and negative electricity to express the properties of electric charge. He also put forward the idea that electric charges cannot be created or destroyed, and later generations discovered the law of conservation of electric charges on this basis.

And Benjamin Franklin was the first to put forward the idea of lightning rod, and the lightning rod created by this avoids the disaster of lightning strikes, destroys superstition, this Lord is also the drafter of the United States Declaration of Independence and the first postmaster of the United States, his contribution to the United States is fully worthy of becoming the historical figure on the largest dollar banknote, John Leto is also familiar with the life of Benjamin Franklin, and after looking at the $100 paper note in his hand for a long time, he decided to stand up and try his luck!