solution of this code in c...

int main() {
  int n, a[10000] = {0}, i = 0, carry, cpy, len, func, neww;
  scanf("%d", &n);
  if(n==1)
  printf("1");
  else
  {
  cpy = n;
  while (cpy != 0) {
    a[i] = cpy % 10;
    cpy = cpy / 10;
    i++;
  }
  while (n != 1) {
    for (len = 0; len < i; len++);
    n--;
    i = 0;
    carry = 0;
    for (i = 0; i <= len + 1; i++) {
      func = n * a[i] + carry;
      a[i] = func % 10;
      carry = func / 10;
    }
  }
  for (i = len; i >= 0; i--)
    if (a[i] != 0) {
      neww = i;
      break;
    }
  for (i = neww; i >= 0; i--)
    printf("%d", a[i]);
  }
}

logic : - suppose you're asked to multiply 25 with 24..

what toddlers do..

25

* 24

100

50 *

600

what we do... 5*24=120, 0 stays, carry 12... then 2*24+12=60.. hence 600. this method is called supercarry. Take an array, use this supercarry method and for every i, print a digit in array[i]. then print the anti-array. If there are extra zeroes in front of the answer, remove them by using..

for (i = len; i >= 0; i--) if (a[i] != 0) { neww = i; break; } for (i = neww; i >= 0; i--) printf("%d", a[i]);

how your multiplication goes..

n=25.

52 006 00831 006303

etc..

when you print the anti-array

the number prints without any problem...