HELP! I'm writing a C program for calculating Permutations and Combinations. When I enter n=5 and r=2 it gives me the correct value. But when I enter n=52 and r=5 the difference for both the Permutation and Combination is 1. nPr=311875199 (instead of 311875200) and nCr=2598959 (instead of 2598960). Also when n is bigger than r it gives me negative values (ex: n=100 and r=5). Is there any way to get the correct value for any two numbers and not just some numbers? This is what I have as my C program:

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#include #include

int main() { int n,r,ncr(int,int); long npr(int,int); long double fact(int); printf("Enter the value of n:"); scanf("%d",&n); printf("Enter the value of r:"); scanf("%d",&r);

if(n>=r){ printf("%dC%d is: %d ",n,r,ncr(n,r)); printf("%dP%d is: %d ",n,r,npr(n,r)); } else{ printf("WRONG INPUT, n>=r"); } } long double fact(int p){ long double facts=1; int i; for(i=1;i<=p;i++) facts=facts*i; return(facts); } int ncr(int n, int r){ return (fact(n)/(fact(r)*fact(n-r))); } long npr(int n, int r){ return(fact(n)/fact(n-r)); }