system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do IQ calculations work and what do they really tell about a person?
gpt
A legit IQ test is administered by a trained professional, and should be a one-on-one test (not a quiz online, not in a group, it should be you and someone with a stopwatch and some flip-books). It will give you an estimate how well you score, as compared to others your age, on of a handful of cognitive functions we currently think are pretty important to have. Verbal skills, nonverbal reasoning, processing speed, and working memory are the most common skills, fluid reasoning sometimes is in there too. 


Those skills are combined into one "Full Scale IQ" score, which has an average of 100, that tells you, on average, how well you do on those skills as compared to others your age. But that 1 number might not mean much if you're really good at one thing but crap at another. And you also might be good (or bad) at other things that are important in life, like long term memory, social skills, academic stuff like reading and math, that the test doesn't measure. And so the IQ may or may not accurately represent how "smart" you appear.