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Re:The Riemann Hypothesis by emilgouliev on Monday September 09, 2019 @07:52PM (#20923796)
you don't need to invoke a concept of area to justify this. you can just think of a grid of dots. since multiplication is repeated addition, each row represents one step of the repeated addition.

2x3 = 3 + 3

...

...

3x2 = 2 + 2 + 2

..

..

..

since rotation doesn't change the number of dots, we expect 2x3 and 3x2 grid of dots to contain the same number of dots, which proves that multiplication is commutative.

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