Minimal Calendar

Last Updated : Oct. 26, 2021

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 This code(written in C) can be used to know 
 the day of the entered date in DD/MM/YYYY format.
 This code works for invalid dates also but gives answer accordingly
 e.g., 32/12/2020 will be assumed as 01/01/2021

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Formula

Day is determined by counting no. of odd days.

Let N be the no. of odd days.

If N = 0, then Sunday

If N = 1, then Monday

If N = 2, then Tuesday

If N = 3, then Wednesday

If N = 4, then Thursday

If N = 5, then Friday

If N = 6, then Saturday

N is given by,

N = (K + [ 2.6M - 0.2 ] + D + [ D/4 ] + [ C/4 ] - 2C ) mod 7,

where K = day, C = Centuries passed, D = year, M = month, [x] is Greatest Integer less than or equal to x. More details of this formula can be found at here