#include <stdio.h>

int main() {
    float kelvin, celsius;
    int lower, upper, step;
    
    lower=0;
    upper=300   ;
    
    step=10;
    
    kelvin=lower;
    while (kelvin<=upper){
        celsius=kelvin-273.15;
        printf("%.0f Kelvin %.2f Celsius\n", kelvin, celsius);
        kelvin=kelvin+step;
    }
    return 0;
}

%.2f means print as a floating point with 2 decimals.

The output is: