Amazon prime stock numbers accurate?

I'm sorry, I'm not sure where to post this.

Are there any amazon prime sellers out there? I'm not selling on amazon, but I am curious about the following

When I have an amazon prime product in my cart, if I change the quantity to 99, it will very often change from 99 to a different number. Does this different number accurately reflect the stock number for that item?

Thanks

Bump, if you have an amazon prime account, I would greatly appreciate if you checked the above

If the item is shipped by Amazon,the number means FBA available units