If you don't know accounting, you might not understand the technical language. Read them if you want and see if they're funny anyway, or don't.
The Missing Error
I checked to see if I'd made a similar mistake to the one with Karen's return, but the only return posted for the company was on a cash purchase, no payables involved. I checked the Accounts Payables Subledger for anything suspicious, scrutinized the purchases themselves, and nothing seemed unusual or tricky. I used the A/P Total sheet to add them up and compare to the general ledger... And I was out $200.
...What? Well, that's a head scratcher. The only posts to the general ledger account were from Cash Payments and Purchases, so I checked there. Still nothing fishy. All the cash purchases had their amounts confirmed on the Bank Reconciliation. There was one thing worth $200, though. The discount amount (posted as a credit to Inventory) for paying a bill early. That shouldn't affect the Account Payable, though; it only made up the difference between the full amount payable (debited and marked as paid) and the discounted amount in Cash. It was a fantastic red herring.
Finally, I found it. The cell reference to total and transfer the Accounts Payable debit column from Cash Payments to the General Ledger was a sum of E3:E140. 140!? That's excessive. Well, it was supposed to go to 14, so what almost certainly happened was that I accidentally added a zero while trying to close the bracket on the Sum function. And what difference did that make? Well, it added in the PR number written in under the column to identify Accounts Payable and confirm that it had been debited appropriately: 200.
I guess the moral of this story is that it's worth it to take the time to total the columns within the special journals themselves, rather than reference the entire column from the Ledger with a Sum function. That would have prevented this from happening.
I went back and input all the updated numbers into the worksheet both on my case Excel file and on AME. They all get correct marks now. It is fixed. And the entire time I was doing that and for ten minutes afterward I would occasionally facepalm and mutter "so stupid..." because it was such a dumb reason to be out in my numbers.
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What Actually Happened with the HST Recoverable Balance
Here's what happened. I thought, earlier, that we actually had the same total in HST Recoverable despite the fact that the professor didn't seem to have the Petty Cash HST amounts included in the total from Cash Payments or anywhere else. It had already been established that I misread the transactions entry for that had to do with Petty Cash. There were two things I failed to see: the increase to $500 from $400, and the HST on Entertainment, which I swear I actually noticed and wondered why I wasn't paying HST on it, and I still didn't see it when I looked again. Muzzy, dizzy eyes after several hours of processing numbers is my only explanation there.
So, I was out by the $19.50 that should have been HST on Entertainment Expense. Fine, but why did I think the totals were the same then?
Well, I thought they were the same at first, but when I took a screenshot of the Paying the Government video, I saw that the cents were out. 50 cents were different, between a $.40 and a $.90. That was maddening. I took a closer look and saw that the professor's total brought over from Cash Payments was different from mine... and the difference was greater than my Petty Cash HST amount, by $19.50, not just 50 cents, but the totals still looked like they were only out by 50 cents. Nothing in this project was that small. It didn't make any sense. I badgered around trying to understand how this was possible when the machine was doing all the math for me (reducing the chance for human error substantially), and carefully checked and double-checked my adding processes over and over again, and put addition and subtraction formulae in empty cells by the side to try to spot the problem because I know a value of $19 can't just disappear in the total...
The problem? My brain had stubbornly refused, even under pressure, even knowing that something was wrong, to make any distinction between 7335 and 7355. Until finally one of my side summations came to the total the professor had, $7355.40, versus my $7335.90 and I saw the difference in more than cents. It took half an hour. Not for the first time, I wonder if I have mild discalculia.
I nearly wept.
I suppose if there is a moral to this one it would be to take a break and let yourself see the problem again with fresh eyes when you're getting invested.
Either that, or a reminder that human senses are fallible and sometimes they will invent problems where none exist just by perceiving little details inaccurately, therefore...
It's not always that important to thoroughly understand an apparent problem if you could just go ahead and solve it. If I had gone over to the Petty Cash transaction, noted that HST was payable on the last expense as well, fixed my numbers and come back, rather than doggedly trying to comprehend why something that ought to be impossible seemed to me to be happening, the total would have been right and the reason would have been evident without spending half an hour going insane wondering why $19 had apparently vanished into the ether.