#include <stdio.h>
main () {
    float f, g, radius, Avogadro;
    f = 2.8;
    g = -1.684;
    radius = f + g;
    Avogadro = 6.02e23;
    printf("%f %6.3f %8.2f\n", radius, -12.81963, Avogadro / 1e19);
    printf("%e %6.3e %8.2e\n", radius, -12.81963, Avogadro / 1e19);
    printf("%g %6.3g %8.2g\n", radius, -12.81963, Avogadro / 1e19);
}