We have 5 people in my family. We cook different meals for ourselves vs. children due to different dietary requirements. So the kids have learned to cook their own things, too, and do so for 2 out of 3 meals each day. If you assume even just 2 openings of the fridge to get ingredients for each meal and put them back, that is 24 openings at a bare minimum. Adding in some snacking and needing more than 2 openings for ingredients when cooking, that isn't hard to envision 40+ openings.
But aside from the arithmetic, I'd think the number of times matters less than how spread out they are. If it opens and closes often during mealtimes, but stays shut the rest of the day, does the number of times it was opened really make a huge difference?