The Simpsons fans stunned after learning why Maggie was scanned in opening credits

*Sing-song voice* "The Simpsooonnnsss"

Those two words alone are hopefully enough to set The Simpsons opening credits rolling through your mind, and not even the age of the 'skip credits' button is enough to make you forget all the scenes they contain.

We have Bart drawing on the blackboard, Homer being irresponsible at the Nuclear Power Plant and Marge not paying enough attention at the supermarket, which leads to her precious baby daughter being scanned at the checkout.

We're all familiar with the sequence, but have you have stopped to really think about it? Why does Maggie get scanned? Does she even have a barcode on her?

Well, it turns out there is a reason for this particular act - it's actually an Easter Egg.

In early episodes of The Simpsons, the cash register charges $847.63 (£683) for the youngest Simpson - potentially not that much in terms of how much a human life costs, but a figure which fit with a fact at the time.

Show creator Matt Groening has previously confirmed that in the year The Simpsons was released (1989) the estimated monthly cost of raising a child in the US was – you guessed it – $847.63.

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The figure was the creator's inside joke, though it has changed over the years.

More recently, viewers could see Marge's total shopping bill come in at $243.26 (£196) before Maggie passes through, at which point it doubles to $486.52 (£392).

Unfortunately, the cost of raising a child hasn't decreased - instead, the creators decided to change the figure to reflect the fact that kids are still costly, without tying themselves to a figure that would quickly change.

Learning that there's an actual reason tied to Maggie being scanned, and that it's not just another quip at how chaotic the family is, has left fans of the show stunned.

After Twitter account Uber Facts shared the revelation last month, one person wrote: "I’ve always wondered about that. Not kidding."

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Another Simpsons fan previously responded to the news with a gif reading 'you just blew my mind', while others couldn't resist pointing out that the cost of raising a child has risen steeply since the show first aired. .

"That’s one month of daycare for an infant (if you’re lucky)," one wrote years after the first episodes.

In case you were wondering, last year analysis from the Brookings Institution revealed that the cost to raise a child in the US now will set you back a whopping $310,000 (£250,000).

With all those zeroes, I think the Simpsons' cash register is going to need a bigger screen.