Each tree can be traversed independently. Each tree is traversed until a leaf node is reached. Those leaf values are summed for all the trees. The sum of all th

Each tree can be traversed independently. Each tree is traversed until a leaf node is reached. Those leaf values are summed for all the trees. The sum of all the leafs plus a base score is then returned. In the case of binary classification that sum is passed through a sigmoid function. For linear regression the sum is returned.