Finding the Factorial of range between 1 to N - c

Question

trying to write a program that would find the factorial of range of numbers starting from 1 to N,N being the final Number to find the factorial for, i have written a non-recursive program.it only works for integers 1 and 2 in the loop, i'm not sure how to fix it because the logic seems fine,also i'm somewhat still a beginner,so i know i'm probably missing something that's obvious,but in any case here's the code :
#include<stdio.h>
int main() {
int firstnumber;
int finalnumber;
printf("this is a program to calculate the factorial of numbers between 1 to N\n");
printf("please enter the final number : ");
scanf("%d",&finalnumber);
int i;
int factorial=1;
for (firstnumber=1;firstnumber<=finalnumber;firstnumber++) {
printf("the factorial of %d is : ",firstnumber);
for (i=1;i<=firstnumber;i++) {
factorial=factorial*i;
}
printf("%d \n ",factorial);
}
return 0;
}

Answer 1

You need to initialize factorial before each calculation.
int i;
// delete this
//int factorial=1;
for (firstnumber=1;firstnumber<=finalnumber;firstnumber++) {
printf("the factorial of %d is : ",firstnumber);
// move the declaration here
int factorial=1;
for (i=1;i<=firstnumber;i++) {
factorial=factorial*i;
}
printf("%d \n ",factorial);
}

Answer 2

Your two loops are redundant: you can calculate factorial for number from factorial of number - 1
This is the programme with one loop only. Complexity O(N).
Pay attention that you will get overflow rapidly by using int.
#include<stdio.h>
int main() {
int number;
int finalnumber;
printf("this is a program to calculate the factorial of numbers between 1 to N\n");
printf("please enter the final number : ");
scanf("%d",&finalnumber);
int factorial = 1;
for (number=1; number<=finalnumber; number++) {
printf("the factorial of %d is : ",number);
factorial *= number;
printf("%d \n",factorial);
}
return 0;
}