Query code: 4_3_7.c

#include <stdlib.h>
#include <stdio.h>

int ispalindromic(int n);

char nums[6];
int i=0;

int main() {

    int x,y;
    int big;
    big=0;
    for (x=999; x>100; x--)
        for (y=999; y>100; y--)
            if (ispalindromic(x*y)) {
                if (x*y > big)
                    big = x*y;
            }

    printf("biggest palindrom: %d\n", big);

    return 0;
}

/* Check if a number is palindomric */
int ispalindromic(int n) {
    sprintf(nums, "%d", n);
    if (strlen(nums)%2!=0) return 0;
    for (i=0; i<strlen(nums)/2; i++) {
        if (nums[i] != nums[strlen(nums)-i-1]) {
            return 0;
        }
    }
    return 1;
}
Results:

4_3_10.c
4_1_10.c
4_7_14.c
4_4_8.c
40_8_13.c
e20_3.c
20_6_14.c
58_4_6.c
187_3_9.c
36_5_2.c