Why is PEMDAS required?

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What makes non-PEMDAS answers invalid?

It seems to me that even the non-PEMDAS answer to an equation is logical since it fits together either way. If someone could show a non-PEMDAS answer being mathematically invalid then I’d appreciate it.

My teachers never really explained why, they just told us “This is how you do it” and never elaborated.

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Anonymous 0 Comments

It’s not strictly “required”, it’s just a defect of the common notation.

If you use other notation, such as reverse Polish notation, operator precedence is not an issue.

For example, 1+2*3 becomes very different if you ignore the operator precedence, 7 if you do it right, otherwise 9.

However, in RPN, you first write the operands, then the operator. This means that the above expression would be:

2 3 * 1 + or if you prefer, 1 2 3 * +, which both can be read from left to right, both yielding the same result.

So, it’s not strictly necessary, just a bug in our way to write math.

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