Mental abacus

Okay, so you know how we use our fingers to help us count, right? Well, some people in places like Asia have come up with a way to do super fast math in their head without using their fingers. It's called the mental abacus.

So, instead of using their fingers, they imagine a big abacus in their mind. An abacus is a tool that looks like a frame with beads on it that can slide back and forth. Each row has beads that represent a different number like the ones place (1-9), the tens place (10-90), and so on. With the mental abacus, people imagine the abacus in their head and use it to do math.

For example, let's say you wanted to add 5 + 7. With the mental abacus, you would imagine moving one bead up in the ones place (because you're adding 5) and seven beads up in the ones place (because you're adding 7). Then you would count how many beads are up in the ones place (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12), and that would be your answer.

Some people who are really good at using the mental abacus can do even more complicated math problems in their head without writing anything down. It takes a lot of practice, but it can be a really helpful tool for doing math quickly!