Interesting story of mathematics in the third grade of primary school
In the formula of surface, each box represents a number, and the numbers represented by different boxes can be the same or different. What is the sum of the numbers represented by these six boxes? In the original formula, the sum of two 3 digits is equal to 1996.
Three digits, no more than 999. The sum of two 3-digit numbers can only be equal to 1998 at most. Now the total has reached 1996, just a little short of the possible value. Squeeze two three-digit numbers into the corner, and there is almost no room to turn around. There are only three possibilities:
999+997= 1996,
998+998= 1996,
997+999= 1996。
In three cases, the sum of the addend and the digits of the addend is the same, which is 52:
(9+9+9)+(9+9+7)=(9+9+8)+(9+9+8)=52。
Therefore, the sum of the numbers represented by the six boxes is equal to 52.
Interesting story about mathematics in the third grade of primary school II
Bell's mother is ill. In order to earn money to treat her, Bear gets up before dawn every day to go fishing in the river and sell fish in the market as soon as possible. One day, as soon as Little Bear set up the fish stall, the fox, the black dog and the old wolf came. When the bear saw a customer coming, he quickly called, Buy fish? I just caught this fish. It's fresh! The fox asked while turning over the fish, how much is a kilogram of such fresh fish? The bear grinned: cheap, four yuan a kilogram. The old wolf shook his head: I am old and my teeth are falling out. I just want to buy some fish. The bear looked reluctant: I'll sell you the fish. Who should I sell the fish head and tail to? The fox wagged his tail and said, Yes, no one wants to buy the rest, but Uncle Wolf has bad teeth and can only eat some fish. I'm telling you, black dog and I have good teeth. One of us buys fish heads and the other buys fish tails. Didn't that help Uncle Wolf and Brother Xiong? The bear clapped his hands, but hesitated: yes, but at what cost? The fox rolled his eyes and replied: 2 yuan 1kg, fish head and fish tail 1 yuan 1kg. Isn't it 4 yuan 1kg? Bear drew a picture on the ground with a stick, and then patted his thigh: OK, let's do it! The four of them started work together, and soon, the head, tail and body of the fish were separated. Once the bear weighed, the body of the fish was 35 kilograms of 70 yuan; Fish head 15 Jin 15 yuan, fish tail 10 Jin 10 yuan. The wolf, the fox and the black dog quickly ran to the Woods with the fish, matched the head, the body and the tail, and then divided them equally.
On the way home, Bear thought: According to 4 yuan 1 kg, I should sell 60 kg of fish to 240 yuan, but now I only sell Bear in 95 yuan. I can't figure it out.
Do you know what this is about?
Interesting story of mathematics in the third grade of primary school
A fisherman, wearing a big straw hat, sat in a rowboat and fished in the river. The speed of the river is 3 miles per hour, and so is his rowing boat. I must row a few miles upstream, he said to himself. The fish here don't want to bite! Just as he started rowing upstream, a gust of wind blew his straw hat into the water beside the boat. However, our fisherman didn't notice that his straw hat was lost and rowed upstream. He didn't realize this until he rowed the boat five miles away from the straw hat. So he immediately turned around and rowed downstream, and finally caught up with his straw hat drifting in the water.
In calm water, fishermen always row at a speed of 5 miles per hour. When he rowed upstream or downstream, he kept the speed constant. Of course, this is not his speed relative to the river bank. For example, when he paddles upstream at a speed of 5 miles per hour, the river will drag him downstream at a speed of 3 miles per hour, so his speed relative to the river bank is only 2 miles per hour; When he paddles downstream, his paddle speed will interact with the flow rate of the river, making his speed relative to the river bank 8 miles per hour.
If the fisherman lost his straw hat at 2 pm, when did he get it back?
Because the velocity of the river has the same influence on rowing boats and straw hats, we can completely ignore the velocity of the river when solving this interesting problem. Although the river is flowing and the bank remains motionless, we can imagine that the river is completely static and the bank is moving. As far as rowing boats and straw hats are concerned, this assumption is no different from the above situation.
Since the fisherman rowed five miles after leaving the straw hat, he certainly rowed five miles back to the straw hat. Therefore, compared with rivers, he always paddles 10 miles. The fisherman rowed at a speed of 5 miles per hour relative to the river, so he must have rowed 65,438+00 miles in 2 hours. So he found the straw hat that fell into the water at 4 pm.
This situation is similar to the calculation of the speed and distance of objects on the earth's surface. Although the earth rotates in space, this movement has the same effect on all objects on its surface, so for most problems of speed and distance, this movement of the earth can be completely ignored.
Interesting story of mathematics in the third grade of primary school
In ancient Greek legend, there was a hero named Achilles. He is a god who can run well. At that time, a philosopher named Zhi Nuo said: No matter how fast Achilles runs, he can't catch up with a slow tortoise. What's going on here? Zhi Nuo said: Let Achilles race the tortoise and let the tortoise start ahead of Achilles 1000 meters. Suppose Achilles can run 10 times faster than the tortoise. At the beginning of the race, Achilles ran 1000 meters. At this time, the tortoise ran 100 meter, which means it was still ahead of Achilles 100 meter. When Achilles finished the next100m, the tortoise was still ahead of him10m. Achilles runs 10 meter, and the tortoise is in front of him again. Achilles can continue to approach the tortoise, but he will never catch up with it. Children will think that there must be something wrong with Zhi Nuo's words: How can a fast runner not catch up with the tortoise? But who can be wrong?
An interesting math story for primary school students, the hero chased the tortoise: since Achilles started chasing the tortoise, he began to calculate the positions of Achilles and the tortoise. During the whole process of Achilles chasing the tortoise, when Achilles reaches the new position of the tortoise, the tortoise will reach the updated position. So, in the process of Achilles chasing the tortoise, Achilles and the tortoise will reach an infinite number of positions, and add up all the distances between every two adjacent positions, and they get the total distance they run in the process of Achilles chasing the tortoise:
The total distance run by Achilles is1+0.1+0.01+0.001+=19 (km).
The total distance traveled by the tortoise is 0.1+0.01+0.001+=1/9 (km).
However, Zhi Nuo made a mistake: he confused the position change process and time change of Achilles chasing turtles.
The endless transposition process of Achilles1km+0.1km+0.01km+0.001km+does not need an infinite time. 10/9 km divided by 1 km/h = 10/9 hours. Within 10/9 hours, Zhi Nuo's statement holds, that is, every time Achilles reaches a position of the tortoise, the tortoise climbs to a new position. But after 10/9 hours, it won't happen again. If Achilles keeps running, he will soon leave the tortoise far behind.