The Last Christmas

Well this is a question of simple arithmetic, isn't it?

The woodcutter grows 120" in the first ten years, 110" in the second ten years, and so on. This simple series adds up to 780 inches, when added to his original height of 300 inches is 1080 inches, or an even 90 feet. The woodcutter will never get any taller.

Clearly the marker will never overtake the woodcutter while he is growing, so the problem becomes when will the tree be ninety feet tall. And that is also simple arithmetic. The marker started at 150", so has another 930 inches to go, or 930 years. But that was ten years ago, so the last Christmas will be in 920 years. Oh no!

But as it happens, this isn't a question of simple arithmetic. It's a question of simple biology. Trees grow upward at their extremities; only the top of the tree is getting higher, not the bottom, which just gets wider.

So never fear, Christmas will always be here!