Sure, you could probably just get yourself some software or an app, but the physicality of the Monthly Budget Calculator lends it an air of authority. It'll sit there, waiting, waiting for you to punch in your expenses so it can tell you if you're on track each month in six different areas of your life: food, apparel, transportation, entertainment, personal care and miscellaneous.
Each month you set how much you want to spend on each, at most, and then punch in your purchases as they happen, which will deduct from your total. No word on what happens if you go over. Angry buzzing? An electric shock? The thing just explodes? Well, it should do one of those things, at least.
The first expense you'll be punching into it is for $20, though, for the calculator itself. File that under "personal care." (Oh, and then $10 for some AAA batteries. "Miscellaneous.") Hey, we've got this down already!