On several YouTube videos, one being this one, the descriptions of these videos include something like:
Recent studies have shown that almost HALF of over 1000 adults tested were unable to pass a maths test designed for FIFTH GRADERS! We put this to the test - can YOU pass a test designed for fifth graders? To pass, you must answer SIX of the seven questions correctly!
I've seen this claim repeatedly repeated on many videos, but I've found no basis in scientific research. Did these studies ever actually take place?