How can a watch tell if it s a leap year or a normal year?

The leap year of the Gregorian calendar is stipulated as follows: the earth's revolution around the sun is called a return year, and the return year is 365 days, 5 hours, 48 minutes and 46 seconds. Therefore, the Gregorian calendar stipulates that there are common years and leap years, and there are 365 days in a common year, which is shorter than the return year, and there are four short days in four years, so one day is added every four years, and there are 366 days in this year, which is a leap year.

However, an additional day in four years is more than four return years, and there will be many days after 400 years, so there are three fewer leap years in 400 years, that is, only 97 leap years in 400 years, so that the average length of the Gregorian calendar year is similar to that of the return year. Therefore, it is stipulated that if the year is an integer hundred, it must be a multiple of 400 to be a leap year, for example, 1900 and 2100 are not leap years.

"A leap in four years" is to add a whole day, in fact, we have an extra 44 minutes and 56 seconds. In this way, every 100 years is 18 hours, 43 minutes and 20 seconds more, and it is nearly 1 day. Therefore, by the 100th year of the Common Era, this year is not counted as a leap year, in order to offset the overcounted time, which is also called "a hundred years without leap".

But this canceled out an extra 5 hours, 16 minutes and 40 seconds, and 400 years offset an extra 21 hours, 6 minutes and 40 seconds, which is almost a day. Therefore, the Gregorian calendar year is a full hundred years, and it must be a multiple of 400 to be a leap year, which is the principle of "one leap in four years, no leap in a hundred years, and a leap in four hundred years". Students who are interested in these things take a look at "100,000 Whys" after class.

Therefore, when the year is a whole hundred, it should be a multiple of 400 to be a leap year.

You're asking about mechanical watches, right?

Perpetual calendar watches have this function, but only if you adjust the year accurately when you use it for the first time.

His principle is that there is a gear in the watch that only rotates once in 4 years, so there is no need to adjust it in a flat leap year.

Therefore, the watch cannot judge whether it is a leap year or not, and the perpetual calendar function can only be realized under the premise of accurate setting.

I can't tell, even if it's a three-question calendar.

Leap years are: 2000, 2004, 2008, 2012, 2016 ......

Ordinary years are: 2001, 2003, 2005 ......The method of judging flat and leap years: generally the number of years is a leap year as long as it is a multiple of 4, and a multiple of 4 is a common year; The number of parts of a whole hundred years must be a multiple of 400 to be a leap year, and a multiple of 400 is a common year.

Classification is carried out after this analysis.

Example: 1840 4=460

There is no remainder, and 1840 is a leap year.

There is a remainder, 1949 is a normal year.

The general year is divided by 4, and the remainder is the ordinary year, and the one without the remainder is the leap year, but if the year is a whole hundred, then the year is divided by 400, and the remainder is the common year, and the one without the remainder is the leap year.

1. Calculation method 1: look at the last two digits of the year, if the last two digits are not divisible by 4, then it is a common year; If it is divisible by 4 and not divisible by 100, it is a leap year.

2. Calculation method 2: When encountering a year where the last two digits are 0, look at the first two digits of the year, if the first two digits are not divisible by 4, then it is a common year, and vice versa is a leap year, for example, 2000 is a leap year, and 1900 is not a leap year.

For example: 2020 is divisible by 4, then 2020 is a leap year, 2000 is divisible by 400, this year is also a leap year, 2019 is divided by 4, the remainder is 3, not divisible by 4 or 400, then 2019 is a common year.

Introduction to Pingnian: Pingnian is a Chinese word that refers to a year in which there is no leap day in the solar calendar (i.e., February 29), or there is no leap month in the lunar calendar. Divide the non-whole hundred years by 4, or the whole hundred years by 400, if not divisible, it is a common year.

In a normal year, February has only 28 days. The ordinary year of the solar calendar is 365 days, the ordinary year of the lunar calendar is generally 354 days or 355 days, and very rarely 353 days.

Introduction to leap years: 1. Ordinary years (years that are not divisible by 100) that can be divisible by 4 are leap years. (e.g. 2004 is a leap year, 1999 is not a leap year); 2. Century years (years divisible by 100) Leap years that are divisible by 400 are leap years.

For example, 2000 is a leap year, and 1900 is not a leap year); 3. Leap year (leap year) is established to make up for the time difference between the number of days of the year and the actual orbital period of the earth caused by the artificial calendar. The year in which the time difference is made up is a leap year. There are 366 days in a leap year (31 days, 29 days, 31 days, 30 days, 31 days, 30 days, 30 days, 31 days, 30 days, 31 days, 30 days, 31 days from January to December, 30 days for destruction, 31 days).

Distinguish between ordinary and leap years

1. Slip a mouth:

There is a leap in four years, a leap in a hundred years, and a leap in four hundred years.

Ordinary years and leap years are easy to judge, and the single digit is odd (singular) without division, and there is a remainder at a glance;

In general, the last two digits of the year, the whole hundred years before two 0s, divided by 4 respectively, the remainder is a common year, and the clean is a leap year.

2. Slip the second by the way:

Divide the year by four, and the rest is a leap year.

The number of days is 366, and the number of days is 29 days in February.

Divide the year by four, and there is a remainder of one, two, three.

Ordinary year 365, February 28 days.

In 2000, it was difficult to calculate the exception.

The divisor is four hundred, and the remainder is a leap year.

Ordinary Year: A year that is divisible by 4 but not divisible by 100 is a common leap year. (e.g. 2004 is a leap year, 1999 is not a leap year);

Century years: Leap years are divisible by 400. For example, 2000 is a leap year, and 1900 is not a leap year);

A common year is a common year except for a leap year.

A leap year was established to compensate for the difference between the number of days of the year and the actual orbital cycle of the earth caused by the man-made calendar. The year in which the time difference is made up is a leap year. There are 366 days in a leap year (31, 29, 31, 30, 31, 31, 30, 30, 31, 31, 30, 31, 30, 30, 30 and 31 from January to December).

Extended Materials. Causes.

The usual explanation is that there are many days, hours, and minutes in a year, and the whole number 365 is still superfluous, and after the accumulation reaches 24 hours in a day, the year in which an extra day is added is a leap year. This explanation just tells everyone how to calculate, and it is something that is set artificially.

The most fundamental reason is that the Earth's orbit around the Sun is 365 days, 5 hours, 48 minutes and 46 seconds (conjunction), which is a tropical year. The common year of the Gregorian calendar is only 365 days, which is about one day shorter than the return year, and the remaining time is about one day every four years, so the fourth year adds one day at the end of February, so that the length of the calendar year of that year is 366 days, and this year is a leap year.

There are 97 leap years in the current Gregorian calendar every 400 years. According to a leap year every four years, the average number of days per year is to be counted out, so that after 400 years, about 3 days will be calculated. Thus three leap years are reduced every 400 years.

Therefore, the Gregorian calendar stipulates that when the year is an integer hundred, it must be a multiple of 400 to be a leap year; A century year that is not a multiple of 400, and even a multiple of 4 is not a leap year.

This is what is commonly said: every four years, no leap in a hundred years, and another leap in four hundred years. For example, 2000 is a leap year and 2100 is a common year.

How to judge common and leap years: Either a leap year or a common year.

Leap year judgment method: Leap year is divided into ordinary leap year and century leap year. A common leap year is a year that is divisible by 4 but not divisible by 100 is an ordinary leap year. A leap year is a leap year that is divisible by 400.

Ordinary year: Refers to a year in which there are no leap days in the solar calendar or no leap month in the lunar calendar.

Leap year: A leap year is a noun in the Gregorian calendar. Where there is a leap day in the solar calendar (February is the twenty-ninth day), the leap (the year is more than the leap year.

The difference in time between the lunar calendar and the return year). Both 2096 and 2104 are leap years, but 2100 is a common year. Therefore, the statement of "every four years" is not correct, and the correct statement should be:

There is an intercalary in four years, no intercalation in a hundred years, and an intercalary in four hundred years".

Leap years are calculated by means of calculation. The exact calculation of a leap year in the Gregorian calendar is based on a return year of 365 days, 5 hours, 48 minutes and seconds. The law followed by the determination of leap years in the Gregorian calendar is that there is a leap every four years, no leap in a hundred years, and a leap again in four hundred years.

How to determine leap years:

Gregorian calendar: a leap year is a year divisible by 4 but not divisible by 100, or divisible by 400; The rest are ordinary years.

Lunar calendar: The Spring Festival is in January, which is basically a leap year; The Spring Festival is in February and is basically a normal year.

Ordinary year leap year formula:

Remember common and leap years, and you have to look at February.

February 28 in ordinary years, February 29 in leap years.

It can be divided by four years, leaving no leap in ordinary years.

Every four years is a leap, and this sentence is the rule of death.

Explanation: The last two digits of the year are not 0 (not a whole hundred years), but an integer multiple of 4, such a year is called a leap year, otherwise it is a common year. The last two digits of the year name are 0 (a whole hundred years), which is an integer multiple of 400, and such a year is called a leap year, otherwise it is a common year.

1. The method of judging the ordinary year.

1. To judge whether the year is a leap year, you only need to look at the last two digits of the year, if the last two digits are divisible by 4, then it is a leap year, otherwise, it is not.

2. When we encounter a year where the last two digits are 0, we look at the first two digits of the year; If the first two digits are divisible by 4, then it is a leap year, and vice versa, it is not.

3. If you encounter that the two digits are 04 at the end of 2004, you can directly regard it as a 1-digit number, if this number is divisible.

4. Then it is a leap year, and vice versa.

2. Calculation method of leap years.

1. Non-integer 100 years: those that can be divisible by 4 are leap years. (e.g. 2004 is a leap year, 2001 is not a leap year).

2. Whole 100 years: 400 divisible is a leap year. For example, 2000 is a leap year, and 1900 is not a leap year);

3. For a year with a large value: if the year is divisible by 3200 and divisible by 172800, it is a leap year. For example, 172800 is a leap year, and 86400 is not a leap year (because although divisible by 3200, it is not divisible by 172800) (this is a return year of 365 days 5h48'''calculated).

Those with a remainder are ordinary years, and those without a remainder are leap years.

How to determine leap years:

1. An ordinary year that can be divisible by 4 and cannot be divisible by 100 is a leap year. (For example, 2004 is a leap year, and 1900 is not a leap year).

2. Century years are intercalary years that are divisible by 400. For example, 2000 is a leap year, and 1900 is not a leap year);

3. For a year with a large value, if it is divisible by 3200 and divisible by 172800, it is a leap year. For example, 172800 is a leap year, and 86400 is not a leap year (because although it is divisible by 3200, it is not divisible by 172800).