I get to review scientific articles in which the authors manage to consistently use principle where they should be using principal, and by keeping this article on dailywritingtips you are actually promoting this nonsense!

I scrolled down to the bottom of the reaction page, simply because I wondered why no-one had corrected your article, many readers will not check all reactions, and simply take your incomplete and misleading advice.

Your bank is not wrong. The information on this site, while it doesn’t say anything wrong, is inaccurate. Principal can be a noun or an adjectice. Principal should be used anytime you are referring to the first or largest of something. So the principal in a loan refers to the largest sum of money. Anything that is not a belief, statement, ideal etc. should use principal. So really people should stop going around using the “Principal is your PAL” slogan, because it leads people to think that on all other occasions one should use “principle” and that is not correct.