The third grade mathematics | the judgment method and practical application of the ordinary year and leap year, and the difficulty is not small, and it is recommended to collect it

Unit 6 of the third grade mathematics volume of the human-taught edition of mathematics is mainly through understanding the knowledge of the leap year of the common year, remembering the judgment method of the leap year of the ordinary year, through everyone's observation, analysis and judgment, can solve the problem of date calculation and estimation in daily life. This part is actually we in the previous study, the year, month and day related issues, has already mentioned the concept of common years and leap years, so to this part of the special talk about the common year leap year, everyone is not so strange, on the basis of the previous understanding, now we will explain the judgment and calculation method of the common year and leap year in detail. In addition, in the process of using the method of judging the common year and leap year to solve practical problems, how to use and master the steps of solving the problem is also the core content of our lesson.

Before the explanation, Teacher Tang summed up the important knowledge points of the leap year of the common year, and everyone could review and study intensively.

1. Ordinary years and leap years

There are 28 days in February and 365 days in the whole year; There are 29 days in February and 366 days in the year.

Second, the method of judging the ordinary year and leap year:

1． There is one leap year every four years and the other three years are common years.

2． Gregorian years that are multiples of 4 are generally leap years, but when the Gregorian year is a multiple of 100, it must be a multiple of 400 to be a leap year. For example, 1900 is not a leap year because 1900 is a multiple of 100 but not a multiple of 400; 2000 is a leap year because 2000 is a multiple of 400.

Third, the method of estimating the day of the week.

Example: Known today Wednesday, another 50 days of the week?

Answer: Because a week is seven days, then by 50 ÷ 7 = 7 (weeks)... 1 (day), know that 7 of the 50 days are more than one day, so the 50th day is Thursday. (Note: The question is asked in another 50 days, so this 50 days does not include today's, here is also a special reminder to everyone, when doing this type of date calculation, we must pay attention to some key words, it determines the direction of the entire topic, determines the right or wrong of this topic, so we must be vigilant. ）

We understand that the common year, the leap year is through knowing that the leap year has 366 days, of which There are 29 days in February, and there are 365 days in the ordinary year, of which 28 days in February, but the method of judging is also judged by the year, so how to judge it? In the next step, we will explore and learn step by step.

Everyone must grasp its two criteria when judging the leap year of the common year, usually the multiple of the year is four, that is, the leap year that can be eliminated, and if there is a remainder, it is the common year. However, when the year is a multiple of a whole hundred, it must be a multiple of 400, that is, the year is divided by 400, and what can be divided is the leap year, and if there is a remainder, it is a common year.

When using the characteristics of the common year and leap year to calculate the date, you must have a comprehensive understanding of the dates of the common year and the leap year, at least you must be able to determine whether it is a common year or a leap year through calculation, in order to determine the number of days in February, and even the number of days in the entire year is 365 days or 366 days.

Through the above understanding of the overall basic knowledge of the common year and leap year big moon and the classic question type analysis, I believe that everyone has a good understanding of the characteristics of the leap year of the common year, and there is basically no problem with its algorithm, then the following consolidation exercise part is from the more common or common examination of the question type, the overall understanding of the date is relatively high, can reflect whether everyone's ability to observe and reason has reached the established requirements, come and show their skills, see if their learning ability has reached the standard.

Written in the end: through the understanding of the common year and leap year and how to judge the year of the common year and leap year by calculation directly determines the number of days of the whole year, so when you calculate and calculate the date, you must first determine the year and then calculate and calculate other dates.