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Related: Culture Forums, Support ForumsSneederbunk
(14,289 posts)Arkansas Granny
(31,513 posts)enough
(13,256 posts)denbot
(9,899 posts)I guess it goes against orders of operations.
Freethinker65
(10,009 posts)JudyM
(29,225 posts)CurtEastPoint
(18,638 posts)demmiblue
(36,838 posts)madinmaryland
(64,931 posts)Kali
(55,007 posts)ProudLib72
(17,984 posts)I seriously did not even understand the question posed by the OP.
lillypaddle
(9,580 posts)this is what I did.
dchill
(38,465 posts)Math does it to me every time.
dem4decades
(11,282 posts)targetpractice
(4,919 posts)Some kind of innate maths going on in my head. No logic.
DBoon
(22,354 posts)unblock
(52,183 posts)27 = 3 cubed
48 = 3 times 16 = 3 times (4 squared)
so, 3^3 + 3*(4^2)
factor the 3:
3 * (3^2 + 4^2)
pythagorean theorem says 3^2 + 4^2 = 5^2, so
3*(5^2)
3*25
75
easy!
pangaia
(24,324 posts)Polly Hennessey
(6,793 posts)BillE
(137 posts)7+8=15
20+40=60
15+60=75
Depending on number, sometimes I do it your way. There are other combinations, whatever breaks it down for easy visualization.
Atticus
(15,124 posts)Merlot
(9,696 posts)Bleacher Creature
(11,256 posts)TygrBright
(20,756 posts)yonder
(9,663 posts)then subtract that sum from the sum of the rounded biggies.
Most of the time I'll round up just one biggie, add the other biggie and subtract the rounded value from the sum of the two biggies.
We're jean-yus-is.
KayF
(1,345 posts)"27 + 40 acres is 67"
LuckyCharms
(17,425 posts)Harker
(14,010 posts)LuckyCharms
(17,425 posts)Harker
(14,010 posts)Midnightwalk
(3,131 posts)SWBTATTReg
(22,100 posts)27+48 is
30+50 =
80 - 5
75
dameatball
(7,396 posts)Harker
(14,010 posts)Then, since I'm sixty years of age, I wonder about what the world will be like should I live another fifteen years.
angstlessk
(11,862 posts)4 + 2 = 6 +1 = 7, so 75
TalenaGor
(1,104 posts)pnwest
(3,266 posts)The Velveteen Ocelot
(115,661 posts)jberryhill
(62,444 posts)If I do 27 plus 48, I start hallucinating.
On edit: oh, as a math problem? Okay...
27 plus 48. Oh shit, its a pair of two digit numbers, so were going to need a strategy here. First, is there something simple about the numbers that makes it easy to break down. Aha, okay... 48 is exactly two days, and 27 is one day and three hours. So its three days and three hours. Three days is 72 hours, so its 72 plus 3 which is 75.
I was subjected to a weird experimental math teaching system in elementary school, so one of the first things I do with a math problem is to see if it is simpler in something other than base ten.
Also, it takes me 15 minutes to add up a golf score.
targetpractice
(4,919 posts)ms liberty
(8,572 posts)CTyankee
(63,901 posts)demmiblue
(36,838 posts)It is about how different people come to the same answer using different methods.
Thank goodness rigid methodologies in education are a thing of the past.
hunter
(38,309 posts)Round up or down to most significant digits, then work backwards from there, if needed.
Then...
7 + 8 = 15, last digit is 5, just as the last digit of the quick answer is 5, so the quick answer is probably correct.
I don't actually think about any of this stuff, I just do it.
Years ago, when every penny counted, I'd keep counts accurate to the cent in my head while grocery shopping. It was partly a game, partly necessity.
I'm probably the last generation of kids to use slide rules and printed paper tables in high school, so that might make a difference.
If I'm doing something beyond in-my-head or back-of-the-envelope stuff, I'll use formal systems that were beaten into me in college physics and chemistry classes, keeping track of all the units, canceling and simplifying where appropriate as I work the problem through, generally to end up with some ugly fraction.
I once worked for a machinist who would frequently do complex set-up problems in his head without reaching for his scientific calculator. Sure, I understood the math, but no way could I do it in my head.
And then of course, there is the Trachtenberg system. It was developed by the Russian Jewish engineer Jakow Trachtenberg in order to keep his mind occupied while being in a Nazi concentration camp.
The Figment
(494 posts)Kaleva
(36,294 posts)Leith
(7,808 posts)27 = 25 + 2
48 = 50 - 2
Take the extra 2 from the 27 and give it to the 48.
You have 25 + 50. Getting 75 is easy then.
A lifetime of doing math and logic puzzles, with some algebra 101, can get you quick answers to math questions.
jg10003
(975 posts)Btw, how come the = sign doesn't show in the subject line?
Recursion
(56,582 posts)I'm usually ahead of myself enough that I know I'll be carrying a 1 for the tens digit.
samnsara
(17,615 posts)JI7
(89,244 posts)IADEMO2004
(5,554 posts)underpants
(182,736 posts)20+40=60
7+8=15
OhZone
(3,212 posts)moved two over from the 27 without really saying it with explicit words in my thoughts.
California_Republic
(1,826 posts)tblue37
(65,290 posts)TlalocW
(15,379 posts)7 + 8 = 15.
60 + 15 = 75
TlalocW
sl8
(13,720 posts)Thank you?
lillypaddle
(9,580 posts)7 + 8 = 15, carry the 1 + 2 + 4 = 7 so 75 is the answer
I think my mind must be fucked, but it all happened in 2 seconds. really.
benld74
(9,904 posts)Response to demmiblue (Original post)
panader0 This message was self-deleted by its author.