I can't prove this but I bet that doing lots of mental Math can help slow down aging. In studying a number of techniques for doing fast arithmetic I notice a number of mental skills at play:
- Pattern recognition. Many tricks involve recognizing and exploiting a pattern.
- Visualization of processes. Multiplying large numbers together requires you to hold a mental image of multiple steps.
- Alertness. Falling asleep will cut way down on your efficiency in every technique!
- Mental speed. Impressing your friends will require you to develop speed in your technique.
- Memory. Efficient arithmeticians memorize more Math facts than others. Some people, for example, find memorizing the squares of all numbers up to 25 to be helpful in certain techniques. Also, you often need to maintain a running total in your head and keep track of carries..
- Concentration. When multiple steps need to happen in a sequence your powers of concentration will improve.
A friend and I were discussing how mental Math could help maintain the plasticity of the brain, its ability to reorganize itself in response to new information. She thinks that doing a number of cross-multiplications every day can keep the brain active as we age. I agree.