Why does clock() function in C from <time.h> header only returns clock ticks in increments of 10's of thousands?

Question

I am curious to know why does the function clock() only returns values in increments of 10,000 and is not able to return values in between.

I have the following code:

#include<iostream>
#include<time.h>
#include<stdio.h>
using namespace std;

int main()
{
    int a;
    clock_t clock_start;
    time_t start1;
    time(&start1);
    clock_start = clock();

    for(int i=0;i<200000;i++)
        cout<<8;

    time_t end1;
    time(&end1);

    clock_t clock_end = clock();

    int b;
    printf("\n\n%d",end1-start1);
    printf("\nClock ticks ?? = %d",clock_end-clock_start);
    return 0;
}

The result is either 0 or 10,000

There is no in-between.

The same situation is happening even if I modify the number of iterations the 'for' loop runs. The values are also multiple of 10,000

What is the reason behind this behavior and what is a practical use case for the "clock" function in this case? It seems quite unreliable to me.