Interesting handwritten newspaper on mathematics for third grade students

Interesting Mathematical Knowledge

1. Two boys each ride a bicycle and start riding towards each other in a straight line from two places 2o miles (1 mile (1.6093 kilometers)) apart. OK. The moment they started, a fly on the handlebar of one bicycle started flying straight towards the other bicycle. As soon as it reached the handlebars of the other bike, it immediately turned and flew back. The fly flew back and forth between the handlebars of the two bicycles until the two bicycles met. If each bicycle moves at a constant speed of 10 miles per hour and the fly flies at a constant speed of 15 miles per hour, how many miles does the fly fly in total?

Answer

Each bicycle is moving at a speed of 10 miles per hour, and the two will meet at the midpoint of a distance of 2o miles in 1 hour. The fly flies at a speed of 15 miles per hour, so in one hour it travels a total of 15 miles.

Many people have tried to solve this problem using complicated methods. They counted the fly's first trip between the handlebars of the two bicycles, then its return trip, and so on, working out those shorter and shorter distances. But this would involve what is called the summation of infinite series, which is very complex advanced mathematics. It is said that at a cocktail party, someone asked this question to John von Neumann (1903-1957, one of the greatest mathematicians of the 20th century.), and he gave the correct answer after thinking for a moment. The questioner looked a little frustrated and explained that most mathematicians always ignored the simple method of solving this problem and resorted to the complicated method of summing infinite series.

Von Neumann had a look of surprise on his face. "But, I use the method of summing infinite series." He explained.

Interesting mathematics knowledge is as follows:

1. Arabic numerals

Arabic numerals were invented by ancient Indians and later spread to Arabia. When they reached Europe, Europeans mistakenly thought they were invented by the Arabs and called them "Arabic numerals." Because it has been passed down for many years and people call it fluently, people still call these numerical symbols invented by ancient Indians Arabic numerals.

2. Jiujiu Song

Jiujiu Song is the multiplication table we use now. As far back as the Spring and Autumn Period and the Warring States Period BC, Jiujiu Song has been widely used by people. There are records about Jiujiu Ge in many works at that time. The original Jiujiu Song starts from "Nine Nine Eighty One" and ends with "Two Two Like Four", with a total of 36 sentences. Because it starts from "Nine Nine Eighty-One", it is named Jiujiu Song.

About the fifth to tenth centuries AD, the Nine-Nine Songs were expanded to include "One, One, One". It was around the 13th and 14th centuries AD that the order of the Nine-Nine Songs became the same as it is now, starting from "一一如一" and ending with "Nine-Nine Eighty-One". There are two types of multiplication tables used in our country, one is 45 sentences, usually called "Xiao Jiujiu"; the other is 81 sentences, usually called "Da Jiujiu".

3. M?bius strip

The M?bius strip is a topological structure with only one face and one boundary. You can use a strip of paper to twist 180 degrees and then glue the two ends together to form a M?bius strip.

Cut the M?bius strip along the center line. The first time, you can get a larger ring; the second time and subsequent times, you will get two rings nested in each other. There will never be a break in the middle, which is the magic of the M?bius strip.