&gt; There was also the very embarrassing case of being called to the blackboard to complete a problem in an elective course on number theory only to draw a blank on what 9 times 7 was.<p>If it&#x27;s any consolation, the great mathematician Alexander Grothendieck (<a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Alexander_Grothendieck" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Alexander_Grothendieck</a>), when asked to supply a prime number (at some point in a lecture)—and being puzzled by the idea of actually naming a <i>specific</i> prime number—famously thought for a while before suggesting 57.  (<a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;57_%28number%29#In_mathematics" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;57_%28number%29#In_mathematics</a>)