163652

10 trunks
100 branches
1,000 twigs
10,000 leaves

In one trunk:
10 branches
100 twigs
1,000 leaves

In one branch:
10 twigs
100 leaves

In one twig:
10 leaves

Answer: 8,879

There are 10,000 leaves before the woodcutter chopped some of the tree.
He removed 1 trunk, so there are 9,000 leaves. Then he removed one branch from another trunk. That would bring the leaf count to 8,900. He removed another twig from another branch, that would bring the leaf count to 8,890. He then plucked one leaf from another twig. That brings the total of leaves down to 8,879. The leaves removed are 1,231.