Max donated 16 collars to the dog shelter . mia donated some leashes. hiw many items does mia need to donate that would require you to regroup to find the total number of items donated?

4.

Step-by-step explanation:

To find the total, we would be adding together Max's donated items and Mia's donated items.

"Regrouping" is just another way of stating that we have to carry in the addition.

If we add 16+1, there is no carrying or regrouping.

If we add 16+2, there is no carrying or regrouping.

If we add 16+3, there is no carrying or regrouping.

If we add 16+4, we must carry (regroup).  This is because 6+4 = 10, so we carry 1 to the tens place.  This is the first time we would regroup this number.