The brain is like a muscle. it needs to be exercised, otherwise it would become weakened. The more you exercise it, the more it’ll be stronger, and the more your thoughts will become clearer. Numbers are especially hard to the brain, because brains aren’t naturally designed for numbers, so math is like a gym weight for the brain.

The opposite can be asked: how memory wouldn’t improve one’s life? I can’t see how it wouldn’t. The lack of memory skills would surely be problematic, especially when the modern life requires dealing with lots of information. Sure, we can delegate these oceans of information to our little bright rectangular stones which we often carry around with us like they were extension members of our bodies, but we’d be delegating our intelligence to things that can’t be intelligent at all (smartphones, which lack the "smart"ness of human brain). To be intelligent is to intellego, to understand, to comprehend. Only living beings can comprehend things. However, in order to comprehend, the brain needs to be used for constant comprehension, the brain needs to be developed through neuroplasticity, which is why improving one’s memory is important.