Find the number of rotations in a circularly sorted array.

To find the number of rotations in a circularly sorted array, you can use a modified binary search. The number of rotations is equivalent to the index of the minimum element in the array. The algorithm works by repeatedly dividing the search interval in half. If the middle element is smaller than its previous element, it's the minimum. If the first half of the array is sorted (i.e., arr[low] <= arr[mid]), the minimum element must be in the second half, so we search there. Otherwise, the minimum element must be in the first half, and we search there.