# Birthday Calculator

Birthday Calculator

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## What is Birthday?

Birthday is a special day that celebrates the anniversary of a person’s birth. It is typically marked with a celebration, such as a party or gathering of friends and family, and is often accompanied by gifts and cake. Birthdays are a time to reflect on the past year and look forward to the future.

## What is Birthday Calculator?

A Birthday Calculator is a tool used to calculate the day of the week on which a person was born. It can also be used to calculate the age of a person in years, months, and days.

## How to Calculate Birthday?

To calculate someone’s birthday, you will need to know the person’s date of birth. You can then use a simple calculation to determine the day of the week on which their birthday falls. To do this, you will need to use the Zeller’s Congruence formula. This formula is used to calculate the day of the week for any given date. The formula is as follows: h = (q + (26(m + 1)/10) + k + k/4 + j/4 + 5j) mod 7 Where: h = the day of the week (0 = Saturday, 1 = Sunday, 2 = Monday, 3 = Tuesday, 4 = Wednesday, 5 = Thursday, 6 = Friday) q = the day of the month m = the month (3 = March, 4 = April, 5 = May, …, 14 = February) k = the year of the century (year mod 100) j = the zero-based century (for example, 19 for the 20th century) For example, if someone’s birthday is June 5th, 2020, the calculation would be as follows: h = (5 + (26(5 + 1)/10) + 20 + 20/4 + 20/4 + 5*20) mod 7 h = (5 + (67/10) + 20 + 5 + 5 + 100) mod 7 h = (5 + 6.7 + 20 + 5 + 5 + 100) mod 7 h = (132.7) mod 7 h = 4 Therefore, the person’s birthday falls on a Wednesday.

Cite this content, page or calculator as:

Andy, Cohen “Birthday Calculator” at

from FreeCalculator.net, https://www.freecalculator.net

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