I know that you believe you understand what you think I said,
   but I am not sure you realize that what you heard is not what I meant.

I know what he sediment, but not what the element.

and.......... would this have been a little more honest? He says pedantically!

(12 + 144 + 20 + 3 x √4) / 7 + 5 x 11 = 9² + 0

Though superscript of ½ does it equally - eg 4^½ in a Telegraphy/Timesy crosswordy sort of way.....
(FWIW √ is Unicode Hash Code √)

Now ---- can anyone devise a limericompute that equates to 42 ? That would be a brain game and a ½
(ligatures are acceptable)