Factorial Code is not working when the given number is very long integer

[Raj_Kumar]

Hi,

Below code is to find "Factorial of a given number"

n=int(input("enter a end range: "))
s=1
for i in range(1,n+1):
    s=s*i
print(s)

for smaller n values code returns correct output. for big numbers (ex: 99 / 999 / 9999) it gives wrong output. that means, The result in output ends with zeros.
Ex: n = 99
Output: (which is wrong output) 933262154439441526816992388562667004907159682643816214685929638952175999932299156089414639761565182862536979208272237582511852109168640000000000000000000000

If n is very long integer i.e. n=100000 (1 Lakh), then output will get struct. we never get output.

What my query is, If I use any long integer ("trillion" or more), I should get the correct result in a very short time with no trouble. Please share tips on this issue.

[ndc85430]

You perhaps want to look up the term "dynamic programming", which is a way to solve problems where you can store and reuse solutions to subproblems.

[deanhystad]

What makes you think this isn't working? The value you display for 99! is the value I get which is the value I see for 99 in factorial tables (ok, I only checked the first 10 digits, the last 10 non zero digits, and counted the zeros). Anything above 5! accumulates zero at the end because 4*5 is 20 and anything times zero is zero. Large numbers are going to take a long time not only because there is a lot of multiplication, but because the multiplication is beyond the native ability of the processor on your machine. Then there is the time it takes to print the output. The output for 100000! is 5700 lines long!