We’re going to talk about a little bit of math and why it’s important for designing and debugging code. y = f(x) is commonly referred to as a “functional notation”. It is a mathematical equation that represents a relationship between two variables, x and y.

Note the order. Red, then Green, then Refactor. Those of you who practice Test Driven Development will deeply understand the importance of this mantra for the three phases of development. I’d like to take it a step further and explain examples of not following the order or spending too much time in the wrong phase.

Those of you who’ve done freelancing will know if you say to the client “Feature X will take 3 weeks at $1,000 a week… that’ll be $3,000 plus tax” they’re going to have a fit. “We want it cheaper, faster, blah blah blah…”

I find myself not paying attention to epics and discussions unless I know the WHY. I literally zone out. Start checking emails and Slack. Half listening for my name or something critical. Before I work on anything that will take more than a day I want to know who’s “paying” for it (the sponsor) and what are the measurable benefits (metrics).

Product Managers focus on the what and why. They care deeply about the who and when. Engineers focus on the how.