Who knows how to quickly calculate the day of the week by looking at the date

First of all, add the date number you want to know, add the month code, and divide it by 7, which is divisible by Sunday; If it is not divisible, the remainder is the number, and the day is the day of the week. If the sum of the date and month codes is less than 7, then the sum is the number of days, and that day is the day of the week.

For example, if you want to know what day of the week May 20, 2006 is, add "20" to the code "0" in May 2006, and the sum obtained is 20, and then divide 20 by 7, and the remainder is 6, then May 20, 2006 is week 6.

Another example: if you want to know what day of the week February 3, 2006 is, then add "3" to the code "2" for February, and sum it to 5. Since 5 is less than 7, February 3, 2006 is week 5.

Since the month code of each year is different, the calculation method of the month code of each year is given below:

First of all, you need to have a calendar, and then find a random day, for example, August 5, 2006, that day is the week 6, just subtract "5" from "6", and the difference obtained is "1", then the code of August 2006 is 1, and the calculation method of the code of other months can be deduced.

This method is written as a formula: the year and month code, the day of the week of the month, and the date number of the month.

Note: When taking the date number of the month, it must be less than or equal to 7; When taking a Sunday, the value is calculated as 7, and the value of the day of the week of the month is greater than the value of the date number.

How do I quickly know what day of the week the corresponding date is?

What is the era number of this year? How many codes are there per month?

Calculate the number of days between two given dates and divide the result by 7. If there is a remainder, the number of days with the remainder is added to the original basis, and then extrapolated, if there is no remainder, it will not change.

For example: today is Wednesday, May 16, 2018, then July 28, 2018 is the day of the week. The 16th is not counted as a day, but from May 16th to July 28th.

1. Calculate how many days are between two given dates

Number of days in May: 31-16 = 15 days.

The number of days in June is 30 days.

The number of days in July is 28 days.

There are several days: 15 + 30 + 28 = 73 days.

2. Reuse the number of days to divide by 7.

73 7 = 10 weeks (3 days remaining).

3. If the remainder is a few, add the number of days with the remainder on the original basis. Since the day of the 16th is not counted, the days are counted from the day after the 16th: the week.

Fourth, week. 5. Saturday. So July 28, 2018 is Saturday.

Speaking of the week, it actually originated very early. In the 7th century B.C., ancient Babylon invented the system of using the week to represent different days, when the ancient Babylonians divided the time of the month into 4 weeks, each week has 7 days, in each week will correspond to 7 gods, respectively, the sun, moon, fire, water, wood, gold and earth gods, and built a seven-star altar, each day to worship the corresponding gods. In 321 BC, the ancient Roman emperor Constantine the Great formally established the week system.

Calculate how many days are in the two periods, divide by 7, and add the remainder to the day of the week at the beginning to get the day of the week. (If the sum is greater than 7, minus 7, it is the number, that is, the day of the week).

For example, if March 1, 2018 is a Thursday, calculate the day of the week on October 1, 2018

The difference is 214 days, 214 7 = 30....4

Thursday + 4-7 = Monday.

October 1, 2018 is Monday.

Summary. Formula: w = y-1) +y-1) 4] -y-1) 100] +y-1) 400] +dy refers to the year is the year d refers to the day is the first day of the year w refers to the day of the week, but to divide by 7 first, take the remainder, no remainder is Sunday, when the remainder is 1, 23, 4, 5, 6, then they are Monday, Tuesday, Wednesday, Thursday.

To calculate the day of the week when a certain day is, first know some basic knowledge of the calendar: 1. Every year there are 31 days in the month and 30 days. 2. A common year in the Gregorian calendar is 365 days, and a leap year is 366 days.

3. Calculation of leap years: those that are divisible by 4 are leap years, but those that are divisible by 100 but not by 400 are not leap years. 4. The year after 1 B.C. is the first year of A.D., which is the first year of A.D.

A.D. 0. 5. January 1, 1 C.E. is a Monday. 6. There are 7 days in a week, and the order is Sunday, Monday to Saturday.

What's the answer? Formula: w = y-1) +y-1) 4] -y-1) 100] +y-1) 400] +dy refers to the year is the year d refers to the day is the first day of the year w refers to the day of the week, but to divide by 7 first, take the remainder, no remainder is Sunday, when the remainder is 1, 23, 4, 5, 6, then they are Monday, Tuesday, Wednesday, Thursday.

To calculate the day of the week, we first know some basic knowledge of the calendar: 1. There are 31 days and 30 days in the month of each year. 2. The Gregorian calendar is 365 days in a common year and 366 days in a leap year.

3. Calculation of leap years: those that are divisible by 4 are leap years, but those that are divisible by 100 but not by 400 are not leap years. 4. The year after 1 B.C. is the first year of A.D., which is the first year of A.D.

A.D. 0. 5. January 1, 1st year of the year of the public friend pants yuan is a Monday. 6. There are 7 days in a week, and the order is Sunday, Monday to Saturday.

For example, October 1st, 2010 National Day, what day of the week? Then y is 2010, d = the sum of each month = 31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 1 = 274 days.

w=2010-1+502-20+5+274=2770,2770 divided by 7 remainder buried in 5, it is Friday.

So strenuous? Yes, calculated by formula, it is like this at the moment.

<>2. After opening Excel**, enter the formula =roundup(day(d9) 7,0).

3. After entering Gongyuanshan =roundup(day(d9) 7,0), press the enter key to find out that the date is the first week of the month.

Zeiler's formula: w=y+[y4]+[c4]-2c+[26(m+1) 10]+d-1 Symbolic meaning: w:

Week; w to 7 modular: 0-sun, 1-monday, 2-tuesday, 3-wednesday, 4-thursday, 5-friday, 6-sat c: century -1 (first two digits) y:

Year (last two digits) m: month (m greater than or equal to 3, less than.