A long time ago (1976) my highschool Math teacher learned me a way to remember a multiplication rule like this:
Consider positive numbers a friend and negative numbers an enemy.
So:
+1 * +1 = +1 (a friend of a friend is a fiend)
+1 * -1 = -1 (a friend of an enemy is an enemy)
-1 * +1 = -1 (an enemy of a friend is an enemy)
-1 * -1 = +1 (an enemy of an enemy is a fiend)
I realize this is not always true in real life, but it helped me memorize this rule.
When I noticed the cache location, it made me remember my highschool teacher.
Congratulations to robespierre50 for the FTF!