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BIRTHDAYPROBABILITY (NumberOfDuplicates,TotalNumberOfDays)

  • is any real number.
  • is the number of days.


  • This function shows the value of the Birthday probability.
  • In , is the additional number of birthday.
  • is the number of days.
  • Birthday probability is the sum of the probability that an event will happen and the probability that the event won't happen is always 1.
  • In a room of 75 there is a 99.9% chance of two people birthday matching.
  • To work out the probability there is no two people will have the same birthday,the following rules to be followed to find the probability that two people will share a birthday:
 P(two people share birthday) + P(no two people share birthday) = 1
 P(two people share birthday) = 1 - P(no two people share birthday).


  1. BIRTHDAYPROBABILITY(3,30) = 0.1384203445582639
  2. BIRTHDAYPROBABILITY(20,432) = 0.3686145731391096
  3. BIRTHDAYPROBABILITY(30.3,765) = 0.44899395029084743

Related Videos

Birthday Probability

See Also