It has been a while since we had a survey on any mathematics topic, so today I’d like to kick one off. What’s your favorite equation, formula, identity or inequality?

Try to keep it to your top 5 so that things don’t get out of hand – but please share which equation, formula, identity or inequality amuse you the most.

So – **What’s your favorite equation, formula, identity or inequality in mathematics and if possible tell us why**? Over to you!

Take into consideration all the branches of mathematics