I'm an idiot

So I was checking my bank account online and I had a negative balance. Uh oh, what happened? I should have plenty of money in there. I was looking at the debits and saw a huge, HUGE payment to the city for sewer, water, sanitation. I looked in my bill pay, and sure enough it was there. I called the bank, they said I was the one who made the mistake. I thought I'd believe that if I'd added a zero to the end, but the numbers had nothing in common. I called the city and asked them to cut me a check for the balance (almost $2000). The girl says, "I'm not sure we can do that. Let me check." WHAT?!? She comes back on and says they will reimburse me if the check doesn't bounce in 10 days. Thanks. Well, at least we will get it back. Luckily we have plenty in our savings to cover it and make it 10 days. So I got to thinking...how could I have made this mistake, and it hit me. I plugged in the balance in my ledger instead of the bill amount to pay. Dumb, dumb, dumb!