What is Mental Arithmetic?
Doing math in your head, no calculator needed
Mental arithmetic is your brain's ability to crunch numbers without external aids: holding digits in your head, performing operations, and keeping track of intermediate results all at once. It draws heavily on working memory and shows up in everyday life every time you split a check, estimate a discount, or convert units on the fly.
The most useful trick for mental math isn't memorizing more facts. It's decomposition: breaking hard problems into easier steps. To compute 15% of $80, most people freeze. But 10% of $80 is $8, half of that is $4, and $8 plus $4 is $12. Decomposition turns one hard problem into three trivial ones. The same principle applies to multiplication, division, and percentages. People who seem to do mental math effortlessly are usually decomposing problems on the fly.
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