Ask the Slot Expert: Double-entry accounting helps me find my record-keeping error

Einstein purportedly said that compound interest was one of man's greatest inventions. Or maybe he said that it is the most powerful force in the universe. Or maybe he called it the eighth wonder of the world. There is some controversy about what he said about compound interest -- if anything at all! -- but let's go with greatest invention.

I would like to make my own nomination for greatest invention: Double-Entry Accounting.

According to the AI Overview that now appears at the top of the results from most of my Google searches:

Double-entry accounting is a bookkeeping system where every financial transaction is recorded in at least two accounts, once as a debit and once as a credit. This ensures that the accounting equation (Assets = Liabilities + Equity) always remains balanced. It provides a more comprehensive and accurate view of a company's finances compared to single-entry accounting, helping to prevent errors and fraud.

Double-entry provides a mechanism to catch errors.

My own double-entry system for tracking my play results recently caught an error I made.

I was rather lazy at the beginning of the year and didn't enter my play results for a few days -- well, weeks -- okay, months. After I broke my royal drought by hitting a royal in mid-February and got a W-2G, I said to myself, "Self," I said, "you have to enter your results now."

After I was dealt a royal flush two months later and received another W-2G, I chastised myself for still not having entered the data and thought that I can't put it off any longer.

It wasn't until I received another W-2G for a royal on a quarter machine with a progressive two weeks later that I finally stopped procrastinating and entered my session results into my database. I use data-entry forms I created in Microsoft Access to enter the data into my SQL database.

I have a mechanism to check my play results entries. In a table named Wallet, I enter my starting bankroll for the day and then how much money I have in my wallet at the end of the day, broken down by the number of hundreds, twenties, fives, and ones and the value of change and tickets. The starting bankroll plus my play results should equal my ending bankroll. If it doesn't, then I made a mistake in either what I entered for my play results or what I entered for my wallet or both.

I set up this system a long time ago when I would usually redeem my tickets before leaving a casino. Then I saw that Jean Scott rarely redeemed her tickets. I realized that using tickets makes record keeping easier. If I was going to be back at the casino in a few days anyway, I might as well keep the ticket.

The only time this procedure bit me was when I had a few hundred dollars in a Red Rock ticket and the casino shut for Covid. I thought that the casino might be closed for gambling, but I could still go in and use a ticket redemption machine. The guard who turned me away at the entrance to the parking lot said that nobody was allowed in the building.

My Wallet table had columns for the bill denominations and change and tickets. I had to do some math to squeeze the value of tickets from multiple casinos and my balances in multiple casino wallets into the columns I had available. That was cumbersome, so I didn't do my wallet reconciliation step.

After I had entered all of my play results, I took my ending bankroll the last time I did the wallet reconciliation procedure, added my play results since then, subtracted the money I deposited in the bank, and compared the total with the cash I had on hand. I was short by a couple of hundred dollars.

No choice now. I was going to have to go back and do wallet reconciliation for each day I played to find my error.

I was reluctant to add columns to my Wallet table because I didn't remember how to alter a data entry form in Microsoft Access to add the new columns to the form. I bit the bullet, added columns so I wouldn't have to showhorn values into existing columns, and re-learned how to design an Access form.

In my play records I note the source (cash, casino wallet, ticket) for the money I put into a machine and how I received the money I cashed out of a machine (casino wallet or ticket). Even months after I played, I was able to calculate how much cash I should have had on hand and ensure that my equation (Starting Bankroll + Play Results = Ending Bankroll) was still in balance.

Data entry with the new columns went much faster than before. It didn't take long for me to find that I had completely missed entering one day's play. When I was finished, the amount of money I had on hand matched the amount I calculated from the data in my database.

Phew. I'm going to enter my play data in a timely fashion from now on.

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