import math


def choose(n,k):
    """Standard Choose function.
    
    :param n: The total sample size.
    :type n: int
    :param k: The number of elements you're choosing.
    :type k: int
    :return: n choose k
    :rtype: int
    """
    return (math.factorial(n)/(math.factorial(k)*math.factorial(n-k)))