Hey Riley, I was reading about the history of mathematics. {{CMD_7}} Really? Tell me about it! {{CMD_8}} Apparently, back in the day, mathematicians worried about writing things like: {{MATH_9}} {{CMD_10}} Why? What's the matter here? {{CMD_11}} Well, they thought of {{MATH_12}} as an {{CMD_13}}area{{CMD_14}}. But {{MATH_15}} was thought of as a {{CMD_16}}length{{CMD_17}}. Apparently they worried whether it made sense to add ``areas'' and ``lengths.'' {{CMD_18}} Hmmm. We don't seem to worry about that now. I wonder why? {{CMD_19}}