What is the easiest algorithm to find day of week?

Here is a standard method suitable for mental computation:

Take the last two digits of the year.
Divide by 4, discarding any fraction.
Add the day of the month.
Add the month’s key value: JFM AMJ JAS OND 144 025 036 146.
Subtract 1 for January or February of a leap year.

What is Zeller’s formula?

Here’s the formula: f = k + [(13*m-1)/5] + D + [D/4] + [C/4] – 2*C. k is the day of the month. Let’s use January 29, 2064 as an example.

What is the day of week?

According to international standard ISO 8601, Monday is the first day of the week. It is followed by Tuesday, Wednesday, Thursday, Friday, and Saturday. Sunday is the 7th and last day of the week.

Who invented the 7 day week?

For centuries the Romans used a period of eight days in civil practice, but in 321 CE Emperor Constantine established the seven-day week in the Roman calendar and designated Sunday as the first day of the week.

What Modulo is used to determine the day of the week?

mod 7
To find the day of the week W, do W = M + D + Y (mod 7) and use 0 for Sunday, 1 for Monday, and so on.

How do you calculate the day of the week in your head?

Calculating the Day of the Week in Your Head

Divide the last two digits of the year by 12.
Find how many 4’s go into the remainder evenly.
Add these three numbers (the divided number and remainders).
Divide the sum by 7 and take the remainder.
Add the remainder to the century’s anchor day to find the year’s Doomsday.

How do I find the day of any aptitude?

Counting of Odd Days:

1 ordinary year = 365 days = (52 weeks + 1 day.) 1 ordinary year has 1 odd day.
1 leap year = 366 days = (52 weeks + 2 days) 1 leap year has 2 odd days.
100 years = 76 ordinary years + 24 leap years. = (76 x 1 + 24 x 2) odd days = 124 odd days. = (17 weeks + days) 5 odd days.

Why is Sunday the first day of the week?

Origins of Sunday as the first day of the Week The “day of the sun” was observed in honor of the Sun-god, Ra, the chief of all astral bodies, making Sunday the first of all days. In the Jewish faith, this places Sunday as the first day of the week, in accordance with the creation tale, as it comes after the Sabbath.

What is the formula of calendar?

1 ordinary year = 365 days = (52 weeks + 1 day.) 1 ordinary year has 1 odd day. 1 leap year has 2 odd days. = (76 x 1 + 24 x 2) odd days = 124 odd days.

Is Sunday or Monday the first day of the week?

Monday is the first day of the week, according to the international standard for the representation of dates and times ISO 8601. However, in the United States and Canada, Sunday is considered to be the start of the week.

Is there an 8th day?

Jesus’ resurrection on Sunday was the catalyst for “the eighth day” innovation in the early church. The early Christians now were convinced that God’s creative activity extended beyond the seven-day week, and so the first day, Sunday, was also the eighth day of God’s work.