“Someone stole my broken calculator, but I don’t know why. It just doesn’t add up”

“Add up” means to make a mathematical sum. “Doesn’t add up” means that something doesn’t make sense.
     
“Someone nicked my broken calculator at work!......it just doesn’t add up!” was posted on Twitter by Brian Pooley on September 26, 2014. “I can’t believe someone stole my broken calculator from work today, it just doesn’t add up” was posted on Twitter by Scott Hoad on June 10, 2015. “I can’t believe someone would steal my broken calculator. It just doesn’t add up!” was posted on Twitter by LB on September 24, 2015. “Someone stole my broken calculator, but I don’t know why. It just doesn’t add up” was posted on Reddit—Dadjokes on May 17, 2023.
   
     
Wiktionary: add up         
Verb
add up (third-person singular simple present adds up, present participle adding up, simple past and past participle added up)
1. (transitive, of a numerical amount) To take the sum of; to total.
2. (intransitive) To accumulate; to amount to.
3. (idiomatic, intransitive) To make sense; to be reasonable or consistent.
 
Twitter
Brian Pooley
@BslashyP
Someone nicked my broken calculator at work!......it just doesn’t add up!
5:44 AM · Sep 26, 2014
 
Twitter
Scott Hoad
@ScottHoad
I can’t believe someone stole my broken calculator from work today, it just doesn’t add up.
1:42 PM · Jun 10, 2015
 
Twitter
LB
@Luce1982
I can’t believe someone would steal my broken calculator. It just doesn’t add up!
5:06 PM · Sep 24, 2015
 
Twitter
Joel
@joelbirdtweets
@Pundamentalism @richardosman someone stole my broken calculator, it just doesn’t add up
6:23 AM · Apr 13, 2016
 
Twitter
💂🏻‍♀️👋🏻вєαя🍻🇬🇧™
@BigBearF1
Someone’s stolen my broken calculator. I don’t understand. It just doesn’t add up
6:00 PM · Aug 4, 2020
 
Twotter
LB
@Luce1982
I can’t believe someone would steal my broken calculator. It just doesn’t add up.
2:12 AM · Jun 24, 2021
 
Twitter 
Day
@Day89
Absolutely gutted to find out that someone has stolen my broken calculator.
It just doesn’t add up.
11:06 AM · Jun 13, 2022
 
Reddit—Dadjokes
Posted by u/Sir_Pluses May 17, 2023
Someone stole my broken calculator, but I don’t know why.
It just doesn’t add up.
   
LaffGaff
Broken Calculator Thief
May 20, 2023 by laffgaff
Someone stole my broken calculator, but I don’t know why.
It just doesn’t add up.
 
Twitter
Robert Wilkinson
@robertwlk
Why would someone steal my broken calculator?
It doesn’t add up.
1:58 AM · May 21, 2023