Why Is The 9/10ths Necessary When Buying Gas?

Yesterday, I was filling up some premium gas at a premium price, and began wondering why the heck they add the 9/10ths to the end of it?  If the oil companies need that extra penny, just take it! Why do they need to bring fractions into my happy fraction-free lifestyle?  Considering that they add a buck (or more) per gallon to the price of gas every summer anyway, I just don’t see the need for the extra 9/10ths of a cent.  Is this something that was a really great idea in the 1920’s when a penny was a big deal?  Or maybe it’s a conspiracy designed by high school math teachers to make us think that fractions are used “in the real world”.  Of course I don’t want to pay more than I already do for gasoline, but that fraction really cramps my style when I’m pumping my fuel.  Did I miss the day in school when they explained why this insanity exists?  Is it common knowledge?  Somebody help!

Jeremy Nutt

Hi, I'm Jeremy.

19 thoughts to “Why Is The 9/10ths Necessary When Buying Gas?”

  1. The fuel companies are technically not charging you an extra 9/10ths of a cent. The are charging 1/10th of a cent less. This is because the true volume of gas you pump is a little less due to evaporation of vapors or fuel that never makes it to your tank. Somewhere, someone who's much smarter than I figured out that 1/10'th of a cent is what those vapors would cost you.

  2. Curtis, you are at the top of your game with the gasoline facts! Is this common knowledge (that I'm clearly missing) or are you "in the know"? 😉 I guess I do feel a little better knowing that they aren't trying to grab an additional penny from me. I do still think fractions crowd me while pumping fuel though!

  3. Hi Jeremy,

    It's *also* due to the same reason that store prices are always $3.99, (which is just a decimal fraction, after all) and not $4 – marketing experts know there's an inherent psychological bias to weight the $ figure more than the cents in buying decisions – hence, you'll always tend to reach for the $3.99 item over the $4 one.

    Love your blog – keep up the good work !!

  4. Curtis

    That doesn't make any sense… .if 1/10 of a cent was lost in vapors when gas was only say .50 per gallon wouldn't the cost of the lost vapors be like 5/10 of a cent now. I think Steve is closer to the truth.

  5. If it was once inteneded to allow for evaporation, it isn't anymore. That thinking would be "by the gallon" (volume) and would fluctuate with the price of gas…a lot more than 1/10th these days!

  6. All your theories on evaporation and conspiracy are uninformed speculations.

    Let me educate our family here. Contrary to belief the penney IS NOT the smallest denominator in our currency ! The "MILL" is there are 10 (ten) Mills to a penny ! The mill has never been removed from use but is no longer in use. Also The term E Pluribus Unum, is incorrect It should be Et Pluribus Unum. We can put a man on the Moon, but we can't spell and don't know our own History..

  7. By the way This is not an April fools joke do your home work and find out

    PS: search the dictionary Webster etc..

  8. if the fuel vapor theroy was correct ,we should get more than the 1/10 of a cant .all gas stations have a fredally mandated VAPOR RECOVERY system installed on their pumps,so that means they are recovering vapor and are reselling them again right?

  9. That’s not a decimal mixed with a fraction. Those are whole numbers in the thousands (hence the humor behind the joke; those prices are appropriate for a cheap car in the States). The commas just make them easier to read. If they were decimals, they would be periods, not commas.

  10. @oldgriz:

    E Pluribus Unum is indeed correct, but slightly contracted. If one were to spell it out, it would be Ex Pluribus Unum –> out of many, there is one. The Latin motto refers to the creation of a single nation out of many colonies/states.

  11. Andrew is correct. “Et” is Latin for “and,” “e” is shortened from “ex,” meaning “from”. If it were “et” and not “e,” the word “pluribus” wouldn’t make sense; Latin is an inflected language, and the word endings denote the meaning of the word in the sentence. Oldgriz, before you start claiming that can’t spell, maybe you should try doing a little research. Interesting fact about mills though, I didn’t know that 😉

  12. Whatever it is guys, we’re still getting ripped off. I wish their surplus would build to the point they’re swimming in gasoline with no sales.
    Yeah. let’s all not buy any gas for a couple days all at the same time. that’ll get ’em squealing. Yeah right.

  13. Matt, maybe they charge so much in Italy so they can keep replacing the gas hoses that are always damaged by the customers autos. Appears that they get ran over alot.

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