1+2+3+ .....+97+98+99+ 100 = ?
The teacher is thinking, now the children must start class! I used this as an excuse to go out, but Gauss stopped me! ! It turns out that Gauss has worked it out. Little friend, do you know how he did it?
Gauss told everyone how he worked it out: add 1 to 100, and add 100 to 1, adding two lines, that is:
1+2+3+4+ .....+96+97+98+99+ 100
100+99+98+97+96+ .....+4+3+2+ 1
= 10 1+ 10 1+ 10 1+ .....+ 10 1+ 10 1+ 10 1+ 10 1
* * * There are one hundred sums 10 1, but the formula is repeated twice, so the answer is equal to < 5050 & gt.
Since then, the learning process of Gauss Elementary School has already surpassed other students, which laid the foundation for his future mathematics and made him a mathematical genius! 1. The milkman has only two bottles with a capacity of 5 liters and 3 liters respectively for him to measure the milk required by customers from the milk tank.
How can I measure a liter of milk with these two bottles without wasting any milk?
2. There are 25 marbles on the plate, and Party A and Party B take them in turn, with a minimum of 1 and a maximum of 3 marbles each time. Whoever gets the last marble loses. How can b be invincible?
"What are you up to, Bill?" The professor said attentively. At this time, his friend was drinking the rest of the coffee in one breath and stood up to leave. "I want to take three girls to travel by bus!" Bill replied.
The professor smiled: "So that's it!" How old are the three beautiful women? Bill thought for a moment and said, "Multiply their ages to get 2450, but they are exactly twice as old as you." ".
The professor shook his head and said, "Very clever, but their age is still a problem." Bill is still here. He added, "Yes, I forgot to say that I am at least one year younger than the oldest." This makes everything clear!
Of course, the professor knows his friend's age. Excuse me, can you work out their ages?
One morning, people found that the safe of a shop had been broken into, and the old man who kept the shop at night was killed and thrown into the river. After the body was salvaged, a stupid policeman found a high-grade pocket watch in the dead man's pocket, but it didn't go. There is no doubt that the time indicated by the watch hand is a very important clue. However, the police forgot the rules of protecting the scene and fiddled with the pointer of his pocket watch several times. The detective asked him if he remembered fiddling with the time indicated by the previous pointer. The police reported, "I didn't look closely at the specific time, but I was deeply impressed that the hour hand and the minute hand just coincided, while the second hand stayed at one point." The detective looked at his pocket watch. The spot on the surface is 49 seconds. He immediately took out the paper and calculated it, and soon determined the exact time when the body was thrown into the river, thus narrowing the scope of solving the case and quickly catching the murderer. Do you know when the hands of the pocket watch will stop?
5. The English poet Jannison wrote a poem, several lines of which read: "Every minute, a person is dying, and every minute, a person is born ..."
After reading it, a mathematician wrote to question it. The letter said: "dear sir, reading famous books makes people feel fast, but there are a few illogical lines, which is really difficult to agree." According to your algorithm, the number of life and death per minute is balanced, and the number of people on the earth is eternal. But you know, in fact, the population on the earth is growing. To be exact, 1.6749 people are born every minute, which is quite different from the number you provided in your poem. For the sake of practicality, if you don't object, I suggest you use a score of 7/6, that is, change the poem to: "Every minute, one person dies, and another one-sixth person is born ..."
6. Three scientists went to Scotland from London to attend a meeting. Soon after crossing the border, they found a black sheep.
"This is very interesting," said the astronomer. "All sheep in Scotland are black."
"This inference is unreliable," replied the physicist. "We can only conclude that some sheep in Scotland are black."
The logician immediately went on to say, "What we really know is that there is at least one black sheep in at least one place in Scotland."
7. A female math teacher in a primary school asked a simple math question: "There are five birds in the tree. The hunter killed one with a gun. How much is left? A clever boy replied, "There are no birds in the tree. The hunter shot down one and scared the others away. The young female teacher looked at the little boy with disdain and commented, "In fact, my answer is very simple. Five minus one equals four." The implication is that there is no need to be smart and think too much. At this moment, the little boy asked the teacher, "Can I test you a question?" "Of course, just take the exam." The teacher answered confidently. The boy started his question: "There are three ladies in an ice cream shop. They all have an ice cream cone in their hands: one is biting; One is licking; One is sucking. Ask the teacher to answer, which of them is married? Hearing this, the female teacher blushed and replied, "It's hard to say. All three of them may be married. "The little boy replied," Actually, teacher, my answer is very simple. Whoever wears a wedding ring will get married.