I’m sure you’ve been in the situation where you go out to a nice restaurant with a large group of friends.  It’s all fun and games until the check arrives and it’s time to figure out how to split the bill.  Usually this means a few ambitious people around the table will whip out their cell phone calculators and a stub of pencil and sit around scrawling figures.  And I don’t know about you, but we always seem to be saying “Okay, we’re still thirteen dollars short.  Everyone throw in a dollar.”

So...Whos good at math?

"So...Who's good at math?"

I like to avoid these situations from the get-go by bringing out the heavy artillery: my TI-83.  I’m kind of a nerd, if you couldn’t already tell by my school.  One nerdy thing I have done in the past is programming my TI-83 with all sorts of useful programs.  I’ve never taken a CS class and I’m definitely not a math girl, but that’s okay.  If you like problem solving and logic in general, you’ll find calculator programming quite addicting anyway.  The program I’m probably most proud of, and the one that I still use even though I’m not taking highschool Calculus anymore, is a little beauty titled “DINNER”.

“DINNER” has the ability to calculate, from any given person’s appetizers/entrees/drinks total, the amount of tax and tip they should pay.  It even allows for adjustment of the percentage of tip you want to leave (10%, 20%, or anything you like).

My gift to you today is the full program of “DINNER”, straight from my TI-83.  My explanation of what’s going on is in italics.  You’ll see that it’s really not too hard to go into the belly of the beast and tinker around to write your own program; you’re basically just dictating to the calculator all the steps you would take manually anyway.  May your group dinners never be dampened by awkward bill-wrangling again.

I hate math, but I love my TI-83 Plus.

I hate math, but I love my TI-83 Plus.


Asking for the total amount “A” spent on appetizers/entree/drinks


:Prompt A

Asking how much “T” you want to tip your server


:Prompt T

Giving the user the results.

Tax due:

:Disp “TAX”

:Disp 0.0825A

Tip due:

:Disp “TIP”

:Disp TA

Total amount due:

:Disp “TOTAL:”

:Disp A + 0.0825A + TA


And it can even be a conversation starter.  You’re welcome.