Ever notice how many life hacks are just simple functions? Like my morning coffee routine is a function with inputs (how tired I am, what time I woke up) that gives an output (how strong to brew it). @karenb97 your budget example is spot on, it's the same thing. Even my drive to work is a function of traffic and how many lights I hit. Once you see it, you can't unsee it.
Oh totally! I heard someone compare functions to making your own kitchen tools instead of doing everything by hand each time. Like if you're figuring out how much food to buy, you could write a "people times burgers" function once and just plug in the headcount each year. Makes total sense for party planning stuff.