I don't know if I approve of it as a standardized test question.  It's kind of like putting "run a 5 minute mile" on a physical fitness test meant for the general population: quite unfair to most regular people.

But as a competition question I think it's definitely fair.

SimpleStacker

since I’m immersed in the system, I’m wringing my hands and thinking why children must be put through such questions that seem to have little relevance to life. but you seem to approve them because of the thinking skills that underpin the solutions