One meaning of per is according to per Merriam-Webster:
according to —often used with as • per instructions • as per usual
Can I use per in the following way?
Per my teacher
Please note that the original title of the question was:
Is per always interchangeable with according to?
Best Answer
You have identified only one definition of 'per'. There are three current, according to Merriam Webster:
The use you identified is the third on that list. Examples of the first ("per bearer") are now considered archaic, but the second ("miles per gallon" or "one plate per person") is quite common, and both are distinct from the third.