The idea here is that in order to ahve
So if your sample of carbon dioxide contains
In your case, the sampel contains
To find the number of moles present in the sample, use Avogadro's constant as conversion factor. Set it up with
#3.33 * 10^(24) color(red)(cancel(color(black)("molecules CO"_2))) * overbrace("1 mole CO"_2/(6.022 * 10^(23)color(red)(cancel(color(black)("molecules CO"_2)))))^(color(blue)("Avogadro's constant")) = color(darkgreen)(ul(color(black)("5.53 moles CO"_2)))#
The answer is rounded to three sig figs, the number of sig figs you have for the number of molecules of carbon dioxide present in the sample.