18

[xarir]

This one is easy to figure out how it works, but it's still fun.


Think of a number.
Add 7 to it.
Subtract 2.
Subtract your original number.
Multiply by 4.
Subtract 2.

18

 

[Plan8]

Alice Cooper wrote about this topic...but somehow I don't think he had math in mind.

 

[Cosine]

A Triviality...

(x + 7 - 2 - x) * 4 - 2 = 18

 

[the_big_E]

even moreso...

(5) * 4 - 2 = 18

 

[Ranger68]

Thrilling.

Not.