What is the logic behind PEMDAS?

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I know some places use BIDMAS as well. Overall though, to someone who knows little about mathematics, why is this the correct order? What’s the exact logic behind it

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Anonymous 0 Comments

It has to do with how we decided to write equations, as other people have stated. What I haven’t seen stated is why that order.

Basically, you can build operations out of “smaller” or “weaker” operations. Multiplication is just repeated addition, exponentiation is just repeated multiplication, tetration is just repeated exponentiation, pentration is just repeated tetration, and so on. Technically, addition is just repeated counting.

If you want to take a LONG time, you can reduce each operation down to addition or even counting, but that is a lot of effort. Instead, you start with the “highest order” operation and work your way down. If you don’t have any tetration or higher, you start with exponents, then multiplication, then addition.

Subtraction, division, exponential roots, and so on are inversions of operations, so they are done at the same time as their “parent” operation.

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