Maybe not a spreadsheet, but everyone with 1 kid knows if they're struggling to pay their bills - and if they are they won't have another. And everyone in a cr

Maybe not a spreadsheet, but everyone with 1 kid knows if they're struggling to pay their bills - and if they are they won't have another. And everyone in a cramped home knows whether they can afford a home with an extra bedroom. And so on. And every couple knows whether they can afford for one of them to take a 5-year-plus career break while starting a big family.