Factorial program in python

The easiest way is to use math.factorial (available in Python 2.6 and above): import math math.factorial(1000) If you want/have to write it yourself, you can use an iterative approach: def factorial(n): fact = 1 for num in range(2, n + 1): fact *= num return fact or a def factorial(n): if n = 0 and that isinstance(n, int). If it's not, raise a ValueError or a TypeError respectively. math.factorial will take care of this for you. Existing solution The shortest and probably the fastest solution is: from math import factorial print factorial(1000) Building your own You can also build your own solution. Generally you have two approaches. The one that suits me best is: from itertools import imap def factorial(x): return reduce(long.__mul__, imap(long, xrange(1, x + 1))) print factorial(1000) (it works also for bigger numbers, when the result becomes long) The second way of achieving the same is: def factorial(x): result = 1 for i in xrange(2, x + 1): result *= i return result print factorial(1000) For performance reasons, please do not use recursion. It would be disastrous. def fact(n, total=1): while True: if n == 1: return total n, total = n - 1, total * n Check running results cProfile.run('fact(126000)') 4 function calls in 5.164 seconds Using the stack is convenient (like recursive call), but it comes at a cost: storing detailed information can take up a lot of memory. If the stack is high, it means that the computer stores a lot of information about function calls. The me...

#Import math Library import math #Return factorial of a number print(math.factorial(9)) print(math.factorial(6)) print(math.factorial(12)) Definition and Usage The math.factorial() method returns the factorial of a number. Note: This method only accepts positive integers. The factorial of a number is the sum of the multiplication, of all the whole numbers, from our specified number down to 1. For example, the factorial of 6 would be 6 x 5 x 4 x 3 x 2 x 1 = 720 Syntax W3Schools is optimized for learning and training. Examples might be simplified to improve reading and learning. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. While using W3Schools, you agree to have read and accepted our

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Introduction to Factorial in Python Factorial, in general, is represented as n!, which is equal to n*(n-1)*(n-2)*(n-3)*….*1, where n can be any finite number. In Python, Factorial can be achieved by a loop function, defining a value for n or passing an argument to create a value for n or creating a prompt to get the user’s desired input. Types of Programming Technique used in Python They can be created with the incremental loops like ‘factorial=factorial*I’ and n*factorial(n-1) Web development, programming languages, Software testing & others n! = n * (n-1) * (n-2) * (n-3) * (n-4) * (n-5) * (n-6) * (n-7) * . . . . . . .* 1 Example: 20! = 20 * 19 * 18 * 17 * 16 * 15 * 14 * 13 * 12 * 11 * 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1 = 2432902008176640000 n n ! 0 1 1 1 2 2 3 6 4 24 5 120 6 720 7 5 040 8 40 320 9 362 880 10 3 628 800 11 39 916 800 12 479 001 600 13 6 227 020 800 14 87 178 291 200 15 1.30767E+12 16 2.09228E+13 17 3.55687E+14 18 6.40237E+15 19 1.21645E+17 20 2.4329E+18 Techniques of Factorial in Python Following are some techniques: Technique #1 – Factorial Program Code: # Python program to determine the value of factorial for a given number # modifying the value keyed in will produce a different result Number = int(input(" Enter the number for which factorial value to be determined : ")) factorial = 1 # to verify that the given number is greater than zero incase it is less than zero then the # message stated below will be printed if Number < 0: print(" ! ! ! ! ! Fact...

I'm trying to build a list of the first ten factorials [1,1,2,6,24,120,720,5040,40320,362880] using only list comprehension. Is that possible? I don't know generators or lambda. Here's my attempt, but I absolutely know why it's wrong: lst = [1] + [i for i in range(1,10)] lst[1:10] = [lst[i-1] * i for i in range(1,10)] print(lst) Just for fun: One-liner mega-hack using list comprehension and an auxililary accumulator (the resulting list itself) to reuse previously computed value s=[]; s=[s[-1] for x in range(1,10) if not s.append(x*s[-1] if s else 1)] result: [1, 2, 6, 24, 120, 720, 5040, 40320, 362880] note: The math.factorial answer is the way when elements are random. Here it's faster because we can reuse previous results. There's also another drawback: the need to store all elements in a list because python does not allow if and assignment like C does. So we have to append to a list and negate the None it returns so if test is True As I said: fun, but still a hack. Your attempt does not work because the list comprehension works element-wise, you cannot refer to lst[i-1] like that. There is a factorial function in math module, however, since you mentioned generators, you can use one like this def mygenerator(): total = 1 current = 1 while True: total *= current yield total current += 1 factorial = mygenerator() output = [next(factorial) for i in range(10)] We could also use our own function but hey, the meaning of the comprehension lists is lost a bit but it is still fun...

Factorial recursion is a method in which a function directly or indirectly calls itself. In mathematics, Factorial means the product of all the positive For example, factorial eight is 8! So, it means multiplication of all the integers from 8 to 1 that equals 40320. Factorial of zero is 1. We can find a factorial of a number using python. There are various ways of finding; The Factorial of a number in Copy Code Copied Use a different Browser def recursive_factorial(n): if n == 1: return n else: return n*recursive_factorial(n-1) #taking input from the user number = int(input("User input : ")) # If the user input negative integer if number < 0: print("Bad Input") else: print("The factorial of", number, "is", recursive_factorial(number)) Output: Copy Code Copied Use a different Browser def recursive_factorial(n): if n == 1: return n else: return n*recursive_factorial(n-1) #taking input from the user number = int(input("User Input : ") # If the user input negative integer if number < 0: print("Bad Input") # If the user inputs 0 elif number == 0: print("The factorial of 0 is 1") else: print("The factorial of", number, "is", recursive_factorial(number)) Output: Copy Code Copied Use a different Browser User Input : 0 The factorial of 0 is 1 FAQs on Factorial Recursion What is Factorial recursion? Factorial of a positive integer is the multiplication of all integers from that number to 1. Factorial is represented by an exclamation mark. If the user inputs a number let’s assume the...

Factorial Program In Python In this article, we are going to create the factorial program in Python. We will learn the iterative and recursive way to find the nth factorial of a number. Additionally, we will also create a program that tells whether a number is factorial or not. Table Of Contents• • • • • • What is Factorial? The factorial of a number is the product of all the numbers from 1 to that number. For example, the factorial of 5 is equal to 5 × 4 × 3 × 2 × 1 = 120. Mathematically ! (exclamation mark) is used to represent factorial. Factorial of a number n is represented by n!. 1! = 1 2! = 2 × 1 = 2 3! = 3 × 2 × 1 = 6 4! = 4 × 3 × 2 × 1 = 24 5! = 5 × 4 × 3 × 2 × 1 = 120 N! = 1 × 2 × 3 × ... × (N-1) × N = N! Note: 0! is equal to 1. Factorial of a negative number is not defined. Iterative Way to Find Factorial An iterative approach is a simple approach where we use loops to iteratively solve a problem. Here we will use For example, if you want a factorial of n then run a loop from 1 to n and multiply all the numbers together. # factorial program in python n = int(input("Enter a number: ")) for i in range(1, n+1): fact = fact * i print(f"Factorial of ") Output: Enter a number: 5 Factorial of 5 is 120 Identify whether a Number is Factorial or Not Above we have seen 2 different programs that calculate the Nth factorial number, now let's create a program that tells whether a number is factorial or not. Here we can apply the reverse approach. Here is the algorithm for thi...

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So i am trying to make a program that finds the factorial using def. changing this: print ("Please enter a number greater than or equal to 0: ") x = int(input()) f = 1 for n in range(2, x + 1): f = f * n print(x,' factorial is ',f) to something that uses def. maybe def intro() blah blah def main() blah main() Not entirely sure what you are asking. As I understand your question, you want to refactor your script so that the calculation of the factorial is a function. If so, just try this: def factorial(x): # define factorial as a function f = 1 for n in range(2, x + 1): f = f * n return f def main(): # define another function for user input x = int(input("Please enter a number greater than or equal to 0: ")) f = factorial(x) # call your factorial function print(x,'factorial is',f) if __name__ == "__main__": # not executed when imported in another script main() # call your main function This will define a factorial function and a main function. The if block at the bottom will execute the main function, but only if the script is interpreted directly: ~> python3 test.py Please enter a number greater than or equal to 0: 4 4 factorial is 24 Alternatively, you can import your script into another script or an interactive session. This way it will not execute the main function, but you can call both functions as you like. ~> python3 >>> import test >>> test.factorial(4) 24 def factorial(n): # Define a function and passing a parameter fact = 1 # Declare a variable fact and set the in...