What can you learn about the days of the week? Calculating the day of the week in your head

Determining the day of the week by date | Online trainer

The exercise is considered completed after 7 correct answers.

The norm for performing the exercise is 2 minutes

To successfully complete the exercise, familiarize yourself with the theory

Determining the day of the week by date | Theory

You can determine the day of the week by date as follows:

1. calculate the day of the week code by adding the serial number of the day in the month, the month code and the year code, and then reduce the resulting sum (if it exceeds 6) to a number from 0 to 6 by subtracting the required number of sevens (or, in other words, by subtracting the corresponding number , a multiple of seven, which can be 7(7x1), 14(7x2), 21(7x3), 28(7x4), 35(7x5), 42(7x6), etc.);
2. Determine the day of the week by the day of the week code.

Days of the week and their codes

Months and their codes

Mnemonic techniques can be used to remember the correspondence between months and their codes.

For example, January is easily associated with the number 6, since the word “January” has 6 letters, and February can be associated with the number 2 based on the fact that February is the second month of the year. But don't forget to decrement the January and February code by one if the year is a leap year.

You can also use your personal associations. For example, if you had your second child in March, then it will be easy for you to associate March with the number 2.

Years of the 21st century and their codes*

Year	TO.	Year	TO.	Year	TO.	Year	TO.
2000	0	2025	3	2050	6	2075	2
2001	1	2026	4	2051	0	2076	4
2002	2	2027	5	2052	2	2077	5
2003	3	2028	0	2053	3	2078	6
2004	5	2029	1	2054	4	2079	0
2005	6	2030	2	2055	5	2080	2
2006	0	2031	3	2056	0	2081	3
2007	1	2032	5	2057	1	2082	4
2008	3	2033	6	2058	2	2083	5
2009	4	2034	0	2059	3	2084	0
2010	5	2035	1	2060	5	2085	1
2011	6	2036	3	2061	6	2086	2
2012	1	2037	4	2062	0	2087	3
2013	2	2038	5	2063	1	2088	5
2014	3	2039	6	2064	3	2089	6
2015	4	2040	1	2065	4	2090	0
2016	6	2041	2	2066	5	2091	1
2017	0	2042	3	2067	6	2092	3
2018	1	2043	4	2068	1	2093	4
2019	2	2044	6	2069	2	2094	5
2020	4	2045	0	2070	3	2095	6
2021	5	2046	1	2071	4	2096	1
2022	6	2047	2	2072	6	2097	2
2023	0	2048	4	2073	0	2098	3
2024	2	2049	5	2074	1	2099	4

There is no need to memorize this table. The year code for the 21st century (2000 - 2099) can be calculated as follows:

1. present the year as an expression: 2000 + X, where X is the number from the last two digits of the year;
2. divide X by 4 and discard the remainder;
3. add X to the result of step 2;
4. if the result of point 3 is more than six, then subtract from it the greatest multiple of seven (but not exceeding the result of point 3).

For example, for 2029: 1) 2029 = 2000 + 29; 2) 29 / 4 = 7 (remainder discarded); 3) 7 + 29 = 36; 4) 36 - 35(7x5) = 1

ordinal day in month = 5;

month code = 5;

year code: 1) 2018 = 2000 + 18; 2) 18 / 4 = 4 (remainder discarded); 3) 4 + 18 = 22; 4) 22 - 21(7x3) = 1

(ordinal day in the month + month code + year code) = 5 + 5 + 1 = 11

Since the resulting sum exceeds 6, we reduce it to a number not exceeding 6 by subtracting the corresponding multiple of seven: 11 - 7(7x1) = 4

Answer: Thursday (day of week code = 4)

ordinal day in month = 26;

month code = 2;

year code: 1) 2039 = 2000 + 39; 2) 39 / 4 = 9 (remainder discarded); 3) 9 + 39 = 48; 4) 48 - 42(7x6) = 6

(ordinal day in the month + month code + year code) = 26 + 2 + 6 = 34

Since the resulting sum exceeds 6, we reduce it to a number not exceeding 6 by subtracting the corresponding multiple of seven: 34 - 28(7x4) = 6

Answer: Saturday (day of week code = 6)

To determine the day of the week using dates of the 20th century, it is necessary to shift the year code of the 21st century forward by 1 day.

ordinal day in month = 12;

month code = 1;

year code: 1) 1953 = 1900 + 53; 2) 53 / 4 = 13 (remainder discarded); 3) 13 + 53 = 66; 4) 66 - 63(7x9) = 3

Since we are dealing with a date from the 20th century, we add one to the year code: 3 + 1 = 4

(ordinal day in month + month code + year code) = 12 + 1 + 4 = 17

Since the resulting sum exceeds 6, we reduce it to a number not exceeding 6 by subtracting the corresponding multiple of seven: 17 - 14(7x2) = 3

Answer: Wednesday (day of week code = 3)

* In a normal (non-leap year) there are 365 days (52 full weeks + 1 day). Therefore, in such a year, relative to the previous one, the day of the week shifts by 1 day ahead.

A leap year has 366 days (52 full weeks + 2 day). Therefore, in such a year, relative to the previous one, the day of the week shifts by 2 days ahead. To be more precise, an additional shift (due to the fact that the year is a leap year) occurs after the end of the month of February. Therefore, for January and February of a leap year (when the shift has not yet occurred), the month code is reduced by one compared to January and February of a regular (non-leap) year.

One of the simplest and most effective exercises for training memory at any age is mental counting. You can come up with many different options for training mental calculation, but a very important point here is the interest in these exercises and the result of the calculations.

We offer for training an exercise on calculating the day of the week for a specific date.

On the one hand, this can be useful in a specific situation to quickly determine on what day of the week you or your friends were born, or on what day of the week was your previous birthday or will be your next birthday. Or maybe surprise your interlocutor a little by telling him that he was born on a specific day of the week.

On the other hand, this is not a simple addition or subtraction exercise. Here you will need to mentally divide, add, and substitute certain numbers instead of the month values. Let's move on to the algorithm for such a calculation.

CALCULATING THE DAY OF THE WEEK BY DATE

Let us first consider the four main parameters for calculations.

Let's take the date - November 20, 1957

The annual index is calculated in such a way that the last two digits of the year are divided by 12. For example, from the year 1957 the number 57 is taken. This number is divided by 12, the remainder is 4 and 9.

The remainder is divided by 4. In our example, the remainder is 9, which when divided by 4 gives a remainder of 2 and 1, but the remainder is not taken into account here.

The three numbers received are added together. So 4 plus 9 plus 2 equals 15.

Each month is assigned its own index, which you just need to remember.

Month | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 |

———————————————————————————-

Index | 6 | 2 | 2 | 5 | 0 | 3 | 5 | 1 | 4 | 6 | 2 | 4 |

For years starting with “one thousand nine hundred...” add + 1

For years starting with “two thousand...” nothing is added.

There is also an additional rule for leap years, which can be recognized by the fact that the last two digits of the year are divisible by 4 without a remainder.

If the reference date refers to January or February leap year, then you need to subtract - 1 from the final number

Let's look at a few specific examples.

1. Calculate the day of the week for the date November 20, 1957

Let's add up all the indices:

Year index - 15 (4+9+2)

Month index – 2

Just the date - 20

Century index - 1

So 15 plus 2 plus 20 plus 1 equals 38.

The result is divided by 7, in our case 38 divided by 7 equals 5 and the remainder is 3.

The week starts on Monday, this is the number 1, and the number 3 corresponds to Wednesday.

Total: November 20, 1957 is Wednesday.

2. Calculate the day of the week for the date 02/10/1928

Let's add up all the indices:

Year index – 7 (2+4+1)

Month index – 2

Just the date - 10

Leap year index – (-1)

Century index - 1

So 7 plus 2 plus 10 plus 1 minus 1 equals 19.

The week starts on Monday, this is the number 1, and the number 5 corresponds to Friday.

Total: 02/10/1928 is Friday.

3. Calculate the day of the week for the date 06/15/2012

Let's add up all the indices:

Year index - 1

Month index – 3

Just the date - 15

Century index - 0

So 15 plus 3 plus 1 equals 19.

The result is divided by 7, in our case 19 divided by 7 equals 2 and 5 as a remainder.

Good day, friends!

I devoted this article to the topic of how to determine the day of the week by date in Excel. Very often, salary department specialists also face this issue, although there are quite a lot of solutions to questions when it is necessary to know whether a given date falls on a working day of the week or not. These tasks include calculating sick leave, determining holidays, determining vacation days, and, indeed, many more tasks where you need to determine the day of the week by date in Excel.

There are several ways to determine the day of week, and in this article we will look at 3 options:

Using a custom format

A very simple way to determine the day of the week by date is done as follows:

• select the ones in which you want to make changes in the date display;
• call the context menu with the right mouse button and select the item "Cell Format";
• in the window that appears, select a tab "Number", in section "Number Formats" you need to select an item "(all formats)" and enter the date format you need in the Type field.

The data formats themselves can be divided into 2 types: full And abbreviated.

• Full format indicated by the full name of the day of the week or month (for example, Wednesday, Thursday, etc.), the full format is indicated “DDDD” for days of the week, “MMMM” for months.
• Short format is displayed in only two letters (for example, Wed, Thu, Fri, etc.) and for this purpose the format “DDD” is indicated for days of the week, “MMM” for months.

Using the TEXT function

In this case, we will use the built-in to determine the day of the week by date in Excel. This function is designed to format a number in a cell and convert it to text.
Using this function, you specify the data source as the first value, and then specify the data conversion format. The format you specify abbreviated or full, as I described above in the first paragraph.

The spelling of the formula looks like this:

=TEXT (A1;"dddd") , the formula returns the text value of the day of the week.

Using the WEEKDAY function

The third option to find out the day of the week by date is using the WEEKDAY function, which belongs to the group "Date and time", there you will find it. This function returns a number from 1 to 7, which corresponds to the day of the week.
The formula looks like this:

=WEEKDAY(A1,2) , Where:

• "A1» – this is the address of the cell where the date is in numeric format,
• "2» – this is a number that determines the type of the return value (there are 3 types: 1 or none – returns a number from 1 (Sunday) to 7 (Saturday), 2 – from 1 (Monday) to 7 (Sunday) and 3 – from 0 (Monday) to 6 (Sunday), we are more accustomed to only type 2).

I think you will find the article “” interesting in which you will find useful tips and examples when working with dates.

And that's all for me! I really hope that that the topic of how to determine the day of the week by date in Excel has been covered and has become useful to you . I would be very grateful for your comments, as this is an indicator of readability and inspires me to write new articles! Share what you read with your friends and like it!

Scientists correlate the days of the week with the planets of the solar system, thereby characterizing each day from the point of view of magic. Therefore, a person born on a certain day also has his own character, temperament and vocation. So, in order to determine what character traits and capabilities each of us is endowed with, you need to calculate what day of the week it was on your birthday and what its meaning is. Using a free online calculation, you can find out how this day affects your character, destiny and magical abilities.

What day of the week was your birthday? Calculate online for free:

You can find out for yourself what day of the week it was on any day and read the description below:

Monday.

This day passes under the sign of the Moon, so Monday people have character traits such as indecisiveness and nervousness; they are contradictory by nature, so they often cannot achieve the desired peaks. Sociable and emotional. They have a rich imagination. Many of them are lonely in life because they are not ready to take responsibility for someone. As for love relationships, they are faithful and sincere.

Magic abilities. On a full moon, they can make a wish by standing in front of an open window. It will definitely come true.

Tuesday.

This day is ruled by Mars, a warlike planet. People born on this day are stubborn, assertive and often aggressive. Although they often doubt the correctness of their actions and words. Tuesday people need someone who can lend their strong shoulder in difficult times, this can be a meek and gentle person, so it is better to choose a soul mate from unobtrusive guys or girls, then the union will be long and happy.

Magic abilities. To see prophetic dreams by order. To do this, you need to lie down before midnight and ask for a dream prediction. Then you can’t get out of bed until the morning.

Wednesday.

This day is ruled by Mercury, so people born on Wednesday will constantly engage in self-improvement. They are conservatives and find it difficult to start something new. Purposeful people, from an early age, clearly move towards their goals. But as soon as what has been achieved is achieved, they begin to get bored and then give vent to the negativity that has accumulated over the entire time. Then they set a goal again and clearly move towards it. In marriage, by the way, they also sometimes need to leave their significant other in a quiet and secluded place, from where they will return calm and spiritual, then the relationship will be strong and stable.

Magic abilities. They use their energy to treat headaches and calm a disordered nervous system by applying the palms of their hands.

Thursday.

Leadership on this day is transferred to Jupiter, which means that Thursday people are excellent organizers and managers. They are leaders in life, which is why weaker people are drawn to them. Among them there are many who are stubborn and intractable; these qualities reach the point of absurdity. At home they are despots, so an ideal marriage is possible with the led and the weak. They are owners, so they do not forgive betrayal.

Magic abilities. Intuition is well developed, so they can predict the future.

Friday.

Venus is the patroness of this day of the week, so people born on Friday are optimistic and cheerful, they are flirtatious and even frivolous to some extent. Their home is always warm and cozy, they have many friends and acquaintances. However, it is difficult for them to find a soul mate, since Friday people cannot live within four walls - they need freedom, which not every lover will like, so it is better for jealous people to immediately refuse marriage with Friday people.

Magic abilities. The sense of profit is well developed, so these people never live in poverty. They always have money and a stable income.

Saturday.

Those born on Saturday are ruled by Saturn, so they can endure a lot. These people are hardworking and smart, they are leisurely but thorough. They don’t like to lead, that’s why they don’t strive for career growth; they prefer home comfort. But in the family they are often unhappy, because they believe that marriage is forever, which means there is no need to take the initiative in maintaining the fire of feelings. They value prudence in partners; others simply become outcasts for them. They are often unhappy in their youth and happy with life in their mature years.

Magic abilities. They never make mistakes about a person, their first impression of someone is always correct.

Sunday.

People born on Sunday are patronized by the Sun, so they are always comfortable in life. They are active and quite successful, although they cannot be called the darlings of fate, since quite often serious problems happen to them. The reason for them is the carelessness of Sunday people - they are lazy and unnecessary. There are few families among them, because they are too lazy to start a family in order to look after someone. They usually go with the flow, which often takes them to the right and profitable place. These people need to learn hard work and assertiveness. A close person who has such traits as prudence and authority helps them achieve a lot in life.

Magic abilities. They have luck and the ability to guess lottery numbers, which they often use.

Below are some shortcuts and tips that will help you find out the day of the week of any date. You can use this trick in the company of your parents or friends and prove your talent to them.

Calculation of the century shift (according to the Gregorian calendar):

1. Take the first double number of a particular year.
2. Find the next largest multiple of 4 after the first double number.
3. Subtract 1 from the number you find.
4. Then subtract the first double number from it.
5. Finally, multiply the resulting value by 2.

Example:

Let's calculate the shift of centuries for the 1900th century.

The first double number of this date is 19.

The next highest multiple of 4 after 19 is 20.

Subtract 1 from this number (20–1).

Now subtract the first double number ((20–1)–19).

Finally, multiply the resulting value by 2.

1900v = ((20-1)-19)*2 = 0.

You can use the Gregorian calendar century offset table below, which groups other century offset values.

Month offset calculation

In one month we have 4 weeks, which means 4x7=28 days. January has 31 days. Remaining days: 31-28=3. This will help in calculating the number for each month.

First, let's designate January as 0.

February = (Number of days in January + remaining days in January) / 7) = (31 + 0) / 7 = 3

March = (number of days in February + remaining days in February) / 7) = (28 + 3) / 7 = 3

April = (Number of days in March + remaining days in March) / 7) = (31 + 3) / 7 = 6

Continue this way until December... Numbers for months:

Month offset table.

Numbers of days of the week

You will need to remember these tables to perform the trick successfully.

Now let's move on to the trick itself.

Remember the formula Centuries Shift + Years Shift + Months Shift + Days Shift

• Days offset = Received days mod 7
• Year offset = (last two digits of year + (last two digits of year/4)) mod 7

If the given year is a leap year and the month is January or February, then years offset = (last two digits of year + (last two digits of year/4)) mod 7) – 1.

Step 1: Ask for any date and prove that you can tell the day of the week of the given date.

Step 2: Take the offset value of this century from the first table, for 1900 it is 0.

Step 3: Calculate the years offset for 86: ((86 + 86/4) mod 7*) = 2

Step 4: Take the month offset value from the second table, for June it is 4.

Step 5: Calculate the days offset: 23 mod 7* = 2.

Step 6: Now add all 4 numbers: 0 + 2 + 4 + 2 = 8.

Step 7: Divide 8 by 7 = 1.

According to the table of numbers of days of the week, the number 1 corresponds to Monday.

Therefore your answer is: Monday.

* mod 7 - Modulo comparison natural number 7. In the above example, 23 mod 7* = 2, that is, 23 - 21 (the nearest smaller integer divisible by 7) = 2. Another example (86 + 86/4) mod 7, 86+21 (complete integer number) = 107 - 105 (nearest number divisible by 7) = 2