Concentration is required, however to reverse the pattern.
Greater focus required with the number of patterns one has to discern to complete task, however, as the pattern is established and repeated, the task becomes easier and the degree of concentration required diminishes. Also requires the establishment of a set of procedural rules and experimenting with which ones are the most effective in arriving at correct answers. I have had bad experiences with math classes and found my emotional and physical responses to even looking at the numbers a great aversive deterrent. Confession - I didn't do all the exercises.