How many cells are there in the brain, and how powerful is a black hole?

We think it's the old fashioned billion (1012), which is a lot. But guess what your brain is mostly made of? It's actually not nerves. For every nerve cell there are ten other cells that are not nerves and they're there to hold it all together like a scaffolding. As for black holes, they are very very powerful. The reason we know this is because it's black. The reason it's black is because it has such a powerful magnetic field that it can't even let light escape. So when light goes past a black hole, it sucks it in like a giant hoover and makes it disappear. That's why it looks black. I can't really answer exactly how powerful a black hole is because the universe is so enormous that if I say that a black hole is 'x' powerful, there will always be one somewhere more powerful that we haven't discovered yet. So I'm going to sit on the fence and say that I can't answer that.