The word vex. “v” is Roman numeral 5, which is odd. “x” is Roman numeral 10, which is even. “e” is the base of the natural logarithm and is irrational (e = 2.718281828…). Its mantissa (the part to the right of the decimal point) is infinitely long.
Two bikes are traveling toward each other at a constant speed of 10 mph. When the bikes are 20 miles apart, a bee flies from the front wheel of one of the bikes toward the other bike at a constant speed of 25 mph. As soon as it reaches the front wheel of the other bike, it immediately turns around and flies at 25 mph toward the first bike. It continues this pattern until the two bikes smush the bee between the two front tires.
The easiest way to think about this is to consider the time. The bikes will take 1 hour to touch, given that they start 20 miles apart and are each traveling toward each other at 10 mph.
Therefore the bee is buzzing back and forth at 25 mph for 1 hour.
Pencil lead. While modern pencils don’t contain lead, that’s still what we call the graphite compound. When real lead was used in pencils it was mined and nearly everyone has used a pencil at some point in their life.
A key. It has a jagged cut in order to fit the lock. A locked door keeps people out and the keyhole is dark. Key rings are a common way to hold a set of keys, and when you’re using a key that one is quiet, but the rest jingle and jangle.