The NEGBINOMDIST function returns the negative binomial distribution. @f is the number of failures, @t is the threshold number of successes, and @p is the probability of a success.
Performing this function on a string or empty cell returns an error.if f or t is a non-integer it is truncated. if (f + t -1) <= 0 NEGBINOMDIST returns #NUM! error. if p < 0 or p > 1 NEGBINOMDIST returns #NUM! error.