# Python Program to find Factorial of a Large Number

## Factorial of a Large Number

On this page we will learn how to find the Factorial of a Large Number in python.

Factorial of a number is product of all the positive numbers less then and equals to the number we are finding factorial. On this page we will see two different ways to solve the Question one by inbuilt function and another by creating a function.

• Input : 5
• Output : 120
• Explanation : 5! = 5 x 4 x 3 x 2 x 1 = 120 ### Method 1 : Without Inbuilt Function

#### Algorithm

• Start
• Pass the value of n to a function
• Initialize a variable name answer with value one
• Run a while loop until value of n is greater then 1
• Multiply the value of n with ans and assign the result in ans
• Decrement value of n by one
• Return the value of answer ### Python code

Run
```def factorial(n):
ans = 1
while n > 1:
ans *= n
n -= 1

return ans
n = 5
print(factorial(n))```

`120`

### Method 2 : Using Inbuilt Function for Factorial

#### Algorithm

• From math library import Factorial Function
• Assign to value to n for which you want to find Factorial
• Pass the value of n to factorial function and assign the result to ans
• Print ans

### Python code

Run
```from math import factorial

n = 5

ans = factorial(n)

print(ans)```

### Output

`120`

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