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No, the order of addition does not matter. You get the correct perimeter regardless of the sequence in which you add the side lengths, because they are the same set of numbers being summed.

Conditions: The same set of side lengths is being summed.; Addition is ordinary real-number addition.

No, the order of addition does not matter. You get the correct perimeter regardless of the sequence in which you add the side lengths, because they are the same set of numbers being summed.

Conditions: The same set of side lengths is being summed.; Addition is ordinary real-number addition.