Take an IQ test for free.

An attempt to assess immediate cognitive abilities without requiring any erudite knowledge base.

In my opinion, this method is so flawed that it is better to abandon this idea altogether until a better way is found. If IQ remained a very narrow scientific tool that most people hadn't even heard of, then it would still be acceptable, but at the moment it is so hyped as an objective and accurate indicator that it is simply not good enough.