### factorial program

The factorial of a non-negative integer n (written n! and read n factorial) is defined by
n! = 1 ,if n = 0 or 1
= 1*2*3*....n, if n > 1
So for instance, 3! = 1* 2 * 3 = 6 and 5! = 1 * 2 * 3 * 4 * 5 = 120 etc.
The number e the natural base of the exponential function is defined as
e = 1/0! + 1/1! + 1/2! + 1/3! + ....1/n!+ .....
Write a program that estimates the value of e using the first few terms up to 1/n!, that is
e = 1/0! + 1/1! + 1/2! + 1/3! + ....1/n!
The user is asked for the value of n, then compute the above sum.
 ``1234567891011121314`` ``````#include using namespace std; int main() { int n, i; long nfact=1; cout << "n="; cin >>n; if ( n >0 ) for ( i = 1;i <=n;i++) nfact += 1.0/i // im confused here. cout << "n!= "<< nfact; ``````

this is all i got so far or is my code entirely wrong ?
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Well you have the basic ideas for a factorial

 ``12345678`` ``````if( n > 0 ) { factorial = 1; for( int i = 0; i < n; ++i ) { factorial *= i + 1; } }``````

How ever you are not understanding the formula for e

it is e = 1/0! + 1/1! .... 1/n!

so say for example we have n = 5 this means:
e = 1/0! + 1/1! + 1/2! + 1/3! + 1/4! + 1/5!
e = 1/0 + 1/1 + 1/2 + 1/6 + 1/24 + 1/120

Basically when they are in order like that you can just multiply the denom by the next value

Basically it would then we could say this

 ``1234567`` ``````double e = 0; //same as 1/0! int denominator = 1; for( int i = 0; i < n; ++i ) { e += 1.0 / ( denominator *= i + 1 ); }``````

I think that is correct I haven't tested I am busy right now sorry but if it's not exactly correct I'll fix it when I have more time.

*edit had a typo with my 5! it was 120 not 60
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I'm not focusing on the logic of the problem but your syntax is off

if/else conditions that have more than one statement require braces
your for loop should also have braces just for good practice

also you should indent after the initial if-conditional and for-loop statement to make it clearer which statements belong to whatever your doing
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You need braces for your if statement and your for loop. otherwise, this won't work.
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 ``12345678910111213141516171819`` ``````#include using namespace std; int main() { int n,i; cout << " Enter n="; cin >> n; double e=0; int denominator=1; for (int i=0; i < n;i++) { e+=1.0/ (denominator *= i+1 ); cout <<"The sum is " <

i dont think the code is right cuz i keep getting numbers that are bigger than what it's supposed to be ( type in n=2, turns out to be 11.5)
and i keep getting "The sum is" multiple times.
Nope I just checked my formula is correct ( according to what he said ) except for one thing. He gave me the wrong formula he said the first value was 1/0! and idk for some reason I was thinking it was = to 0 but thats undefined..the real formula for find e is 1 + 1/1 , + 1/2 + 1/3 + 1/n.. The reason you got 11.5 for 2 idk you must have outputted a one first on accident.

I fixed the formula by changing intial value of e to 1 and I moved the denominator *= outside of the e += to make it look neater.
 ``123456789101112131415`` ``````#include int main() { const int n = 20; double e = 1.0; int denominator = 1; for( int i = 0; i < n; ++i ) { denominator *= i + 1; e += 1.0 / denominator; } std::cout << e << std::endl; }``````

Cheers.

Oh and you are getting the sum is multiple times because you have it inside of the for loop.
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Purely for reasons of style, I'd prefer to avoid the `i + 1` - can't explain why, it is just not aesthetically pleasing.
 ``12345678910111213141516`` ``````#include int main() { const int n = 20; long double e = 1.0L; long double denominator = 1.0L; for (int i = 1; i <= n; ++i ) { denominator *= i; e += 1.0L / denominator; } std::cout.precision(20); std::cout << e << std::endl; }``````
when i enter 2 for n, is it suppose to print 2 and 2.5?? isnt it suppose to just print 2.5?
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Are you sure the first 2 isn't the input?

*edit
It should output 2.5 since 1 + 1/1 + 1/2 = 1 + 1 + .5 = 2 + .5 = 2.5

I see your problem maybe it's because you have the n = ... output and never put an endl;
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when i put endl after it it adds another 2....
i think its easier if u just look at my code.
 ``1234567891011121314151617`` ``````#include using namespace std; int main() { int n,i; cout << "Enter n="; cin >> n; double e=1.0; int denominator=1; for (int i=0; i < n;i++) { e+=1.0/ (denominator *= i+1 ); cout << e<

ok it worked out fine somehow when i put the cout out of the loop and deleted all the endl;
Do you know why it works now without all the endl?
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because you have the output inside of the for loop switch line 14 and 15
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