A story about elementary school mathematics

# Children's Story # Introduction The following is a story about elementary school mathematics compiled for everyone. Welcome to read!

In geometry, complementary angle and complementary angle are applications of complementary ideas. However, when the right angle is a complete set, the relationship between the two angles is not complementary, but complementary.

Let's share a short story about mathematics, hoping to inspire you. The excellent education teacher has compiled relevant materials for your reference:

Once upon a time, there was a great warlord in Shandong Province. At the beginning of a meeting, he wanted to call the roll to see who came, but they didn't come. But the number of people attending the meeting was large, and it was very troublesome to call the roll, so the ignorant warlord thought of a "way". He shouted loudly:

"Raise your hand if you don't come!"

He thinks that there are always a few people who have not come. As long as you know who didn't come, you don't have to call the roll. The people present at the meeting looked at each other, puzzled.

In mathematics, set is an important basic concept. People who should attend today's meeting formed a collection. Among them, the people who actually arrived are part of the people who should be there. We call the people who should be there the "complete set" and the people who actually arrive there the "subset". What has not arrived is also a part that should have arrived, so it is also a subset. The subset of people who have arrived and the subset of people who have not arrived are exactly the complete set of people who should arrive. We call these two subsets complementary sets. In order to understand the subset of "real people", the warlord turned to understand the complement of this subset-the collection of those who have not arrived. This method is good. But because it was divorced from reality, it made a big joke.

The concept of "complement set" is often used in our life. What time is it now? It's two minutes to three. I don't say 2: 58 here, because 2 minutes to 3: 00 is simpler and clearer. We often see in TV and novels that when public security personnel solve a case, they always exclude suspects who have been proved impossible, thus narrowing the scope of suspects. The idea of complement set is also used here.

In primary school, when learning mental arithmetic and quick calculation, complement has many uses. The formula of carry addition is "one plus one minus one", and the formula of abdication subtraction is "one plus one minus one". There are also many places where complement is used in the calculation of multiplication speed. 9 plus 1 gives 1 0,9 and1which can be regarded as complementary. Similarly, 97 and 3,999 and 1 are complementary. The reciprocal relationship and reciprocal relationship between the beginning and the middle can also be understood as complementary relationship. Here are a few examples:

Example:1457-98 = 457-100+2 = 357+2 = 359.

Here, 98 and 2 are complements. Subtracting 98 is converted into adding its remainder 2.

Example 21500 ÷ 25 =1500 ÷ (100 ÷ 4)

= 1500÷ 100×4

= 15×4

=60。

Here, 25 and 4 are complementary. Divided by 25, it is converted into complement 4 times 25.

Example 34.88×1.25 = (4.88÷ 8 )× (1.25× 8).

=0.6 1× 10

=6. 1

Here 1.25 and 8 are complements. Multiplied by 1.25, converted into divided by its complement 8.