An acronym or initialism can become so familiar that we forget what it stands for and add one of its own words back. A pin, or personal identification number, already has “number” in it, so adding “number” is redundant. ATM (an initialism, since it’s not pronounced as a word) stands for automated teller machine, so “machine” is redundant. (In 2001, New Scientist magazine named these kinds of redundancies RAS Syndrome. RAS stands for “redundant acronym syndrome.” Who says scientists are dull?)
So stop using your pin number at the ATM machine. Forget about the LCD display on your PC. Don’t take the GRE exam or worry about the APR rate for your student loan or cashing out of your IRA account. And never look at a UPC code.
There. Saved you seven words. You’re welcome.