my nifty little exponent program

hello all. I'm a beginning programmer and I thought that I would try to write a program that would take a digit and raise it to a large number. It works pretty well and all, but it starts returning all zeros for number larger than 4^15. I would appreciate it if anyone could tell me why? Thank you

int add=0;

int mypow=0;

int diff=0;

int base=0;

int carry=0;

int lnumber[99]={0};

///////////////////////////////////////////////

void remain(int fnum, int fnum2)

{

for (int k=0; k<100; k+=10)

{

if (fnum*fnum2>=k)

{diff=fnum*fnum2-k;carry=k/10;break;}

}

}

//////////////////////////////////////////////

void mult(int farr[], int foper)

{

for (int i=99; i>0; i--)

{

add=carry;

remain(farr[i], foper);

farr[i]=diff+add;

}

}

////////////////////////////////////////////

void power(int farr2[],int fexp,int fbase)

{

for (int i=1;i<fexp;i++)

{mult(farr2,fbase);}

}

////////////////////////////////////////

#include <iostream>

using namespace std;

int main()

{

cout<<"enter base";

cin>>base;

cout<<"enter exponent";

cin>>mypow;

lnumber[99]=base;

power(lnumber,mypow,base);

for (int i=0;i<100;i++) {cout<<lnumber[i];}

return 0;

}