What do the +numbers next to the upcoming chests shown in the chest cycle mean?

On the home page of a player profile, right below their achievement badges, there is a section labeled, Upcoming Chests. In that section a shows pictures of the upcoming 15 chests, 3 rows of 4, and 1 row of 3. Underneath the first pic. is the word next and under each of the other pictures show an amount of time. (i.e. 8h, 16h,
1d 4h, etc.) Obviously, that is showing when each chest will be unlocked based on the unlock times, given a player doesn’t use gems or a key to unlock it. All of that I understand. My question is about this next piece. In the upper right hand corner of the picture of each chest, there is a small + followed by a number. In my profile, the first nine are in sequence (+1, +2, +3, etc.). After the first nine, some increase dramatically and there doesn’t seem to be any pattern they follow. What do the numbers after the + mean? Sorry for having to right out such a long description just to ask a simple question. My phone wouldn’t allow me to upload an image. Thank you bearing with me and I appreciate it all of you but that goes double for whoever answers to question!

These are the placements in the queue. The section shows all your next few chests, 8 i think, and afterwards the most relevant ones. Instead of showing a queue of hundreds of chests these are the highlights