When someone asks you to add 48 + 27, what happens in your head?

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When someone asks you to add 48 + 27, what happens in your head?

Jim K.
Handyman · Pittsburgh, PA · Member since 2018 · 5k+ posts · 13k+ votes

I'm really curious to see how other DIY investors and landlords answer this mental addition question versus the general population.

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Russell BrazilBusiness Member
Moderator
Real Estate Agent · Washington, D.C. · Member since 2012 · 17k+ posts · 30k+ votes
5y

I shift 2 from 27 to 48, then add 25 and 50 to get 75. 

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  • David Lee Hall, III
    Rental Property Investor · Pittsburgh, PA · Member since 2019 · 530 posts · 511 votes
    5y

    Um, Jim, not gonna lie, weirdest question I have ever seen in a RE forum. :-)

    I add 7 then 20. 

    34Reply
  • Russell BrazilBusiness Member
    Moderator
    Real Estate Agent · Washington, D.C. · Member since 2012 · 17k+ posts · 30k+ votes
    5y

    I shift 2 from 27 to 48, then add 25 and 50 to get 75. 

    [email protected]301-893-4635Podcast Guest on Show #192
    District Invest Group545 Reviews
    WebsiteView Page
    50Reply
  • Karl B.
    Rental Property Investor · Erie, PA · Member since 2015 · 1k+ posts · 2k+ votes
    5y

    I had the 20 to 48 and then I add the 7 to 68 to get 75. 

    Hopefully this will shed light as to why I turn into a werewolf during full moons and run around howling looking for value-add real estate deals. 

    49Reply
  • Dawn P.
    Rental Property Investor · Sumter, SC · Member since 2015 · 334 posts · 531 votes
    5y

    I also shift 2 to 48 to get 50, then just add 50 and 25.

    13Reply
  • Mike Dymski
    Investor · Greenville, SC · Member since 2016 · 5k+ posts · 13k+ votes
    5y

    My mind adds the 4 and the 2 plus the carry over.

    16Reply
  • Matt Groth
    Contractor · Grand Marais, MN · Member since 2016 · 249 posts · 417 votes
    5y

    I'm in the minority so far, but I add 40 plus 20, then add the 15. I am waiting for the reply of "full on panic!!!!"

    47Reply
  • Jill F.
    Investor · Akron, OH · Member since 2016 · 2k+ posts · 4k+ votes
    5y
    (40+20) 60+ (8+7) 15 =75
    36Reply
  • Tyler Bushey
    Investor · Biddeford, ME · Member since 2017 · 282 posts · 180 votes
    5y
    Originally posted by @Jill F.:
    (40+20) 60+ (8+7) 15 =75

    Same for me!

    11Reply
  • Kimberly Carver
    Member since 2020 · 119 posts · 56 votes
    5y

    @Jim K. Take 2 from 27 to make the 48 50, then 50 plus 25 is 75 is how I would do in my head, or would do 8 plus 7 is 15, carry the 1, 4 plus 2 plus 1 is 7 - also 75.... quickly do both ways in my head to check my work :)

    2Reply
  • Jim K.
    OP
    Handyman · Pittsburgh, PA · Member since 2018 · 5k+ posts · 13k+ votes
    5y

    Thanks so much for responding. I saw this question elsewhere. The standard "math person" way seems to be what @Russell Brazil and @Dawn P. do. @Jill F. does it the way it was taught to me in my NY primary and secondary school experiences. @Mike Dymski and @Matt Groth take what I see as the European approach to carrying over (guys, it may just be how basic math was done in your state or local curriculums, IDK).

    @Karl B. and @David Lee Hall, III both use the same basic mental math shortcut approach.

    But here's the thing, guys -- I cannot help but look at that and see 48 hours as two days and 27 as one day (24 hours) plus three hours. So I do 48 + 24 = 72 (three days), then add 3. It just seems inconceivable to me that people would do it mentally any other way. And I'm not saying my way is better, I'm wondering why it works that way for me.
    @Matt Groth

    3Reply
  • David Lee Hall, III
    Rental Property Investor · Pittsburgh, PA · Member since 2019 · 530 posts · 511 votes
    5y
    Originally posted by @Jim K.
    I cannot help but look at that and see 48 hours as two days and 27 as one day (24 hours) plus three hours. So I do 48 + 24 = 72 (three days), then add 3... I'm wondering why it works that way for me.

    @Matt Groth

    I think you would want to see why you turn the numbers into days. Did you used to ever be on a very regimented schedule (military maybe)? If you can identify that, you may know why you do it with simple addition. I could see if you always moved cases of a product as a supplier for 30 years, that you would do mental math in “cases” as it would be natural to you (a case could be 20, 24, 30, etc.).

    3Reply
  • Scott Mac
    Austin, TX · Member since 2019 · 5k+ posts · 5k+ votes
    5y
    Originally posted by @Jim K.:

    I'm really curious to see how other DIY investors and landlords answer this mental addition question versus the general population.

    40+20=60

    8+8=16

    16-1=15

    15+60=75

    (or I excel it).

    2Reply
  • Jim K.
    OP
    Handyman · Pittsburgh, PA · Member since 2018 · 5k+ posts · 13k+ votes
    5y

    @David Lee Hall, III

    Not military, but it's probably linked to time management. I have renovation periods now where I have to manage my time very well, and structured time management was a regular part of my life for quite a few years as a teacher. But it's weird as hell to see the outcomes like this.

    3Reply
  • Jill L Ripley
    Real Estate Agent · Plymouth, MA · Member since 2019 · 19 posts · 6 votes
    5y

    @Jim K. I take 2 from 27, to make 48= 50 and whala adding 25 is easy peasy to get to 75🧐

    4Reply
  • Jim K.
    OP
    Handyman · Pittsburgh, PA · Member since 2018 · 5k+ posts · 13k+ votes
    5y

    @Scott Mac

    Thank you, Scott. That's the second shortcut approach I saw elsewhere -- and predictably, from an experienced finance guy.

    1Reply
  • Jim K.
    OP
    Handyman · Pittsburgh, PA · Member since 2018 · 5k+ posts · 13k+ votes
    5y
    Originally posted by @Jill L Ripley:

    @Jim K. I take 2 from 27, to make 48= 50 and whala adding 25 is easy peasy to get to 75🧐

    Yes, that's the good-at-math mental shortcut approach. This is why my right hand's fingers are so crooked and I'm just glad I'm not missing any of them.

    0Reply
  • Jill L Ripley
    Real Estate Agent · Plymouth, MA · Member since 2019 · 19 posts · 6 votes
    5y

    @Jim K.😂

    0Reply
  • Maria Taylor
    New to Real Estate · Roseville, MI · Member since 2021 · 33 posts · 14 votes
    5y

    I also add 60 and 15

    1Reply
  • Pat L.
    Rental Property Investor · Upstate, NY · Member since 2012 · 3k+ posts · 3k+ votes
    5y


    Using the INSANE NEW math my grandsons public school enforced he would have had to decompose the numbers AND show his work or get a zero regardless of the solution.

            48      +     27    =

          /     \         / \

      40          8   20       7

            40    +    20    =  60

               8    +      7   =  15

              60  +   15  = 85

    His public school went 'covid-hybrid-zoom', so now we send him to a private school where they teach him how to solve MATH the way we did in the dark ages. His has since excelled in math, reading & ALL aspects of elementary ed. Then again the class size is 8 not 35.

    7Reply
  • Tim Hager
    Member since 2021 · 1 post · 8 votes
    5y

    I turn 48 into 50 and 27 into 30 and get 80 then take the 5 I added in the beginning away and get 75

    8Reply
  • Sarah Lewis
    Investor · Chicago, IL · Member since 2017 · 40 posts · 33 votes
    5y

    I think " 4' plus 2' 3" = 6' 3" (six feet, three inches)

    3Reply
  • Kevin Manz
    HVAC Tech · Fort Wayne, IN · Member since 2015 · 423 posts · 223 votes
    5y

    I reach for my phone and hit the calculator app

    9Reply
  • Heidi Dunn
    Realtor · Indian River, MI · Member since 2015 · 16 posts · 6 votes
    5y

    @Tim Hager same for me.

    1Reply
  • Joshua D.
    Investor · Columbus, MT · Member since 2013 · 1k+ posts · 1k+ votes
    5y

    @Jim K.

    I would take the 23 and subtract 7 and then multiply by 4 to get the approximate square footage of my yards seasonal rain fall in the post monsoon quadrant...

    But on a more serious note I would just take out my phone and use the calculator. Cuz I HATE math...

    0Reply
  • Dennis Wayne
    Member since 2020 · 339 posts · 356 votes
    5y

    I take 48 then add 30 to get 78 then I just subtract 3 because I used 30 number instead of 27

    This sounds crazy but it’s much much faster in my mind to do math this way

    7Reply
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