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So You're a Mathematician? - September 19, 2009
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Lmao! As a math geek who can't manage simple arithmatic, I whole-heartedly approve!

as a recent phd graduate of mathematics, I get asked these kinds of questions all the time... and I still don't know what 11 x 13 is!!

11 x 13? Plenny!

My resopnse would be "No 1 cares. I've said this be4. This is the 3rd time."

A friend of mine once said "I majored in Mathematics, not Arithmetic!".

143. Sheesh, it's easy multiplying by eleven; just multiply by ten and add the original.

Wow. Why is it that I have never heard it put that simply before? All my years of school (including graduate school) and I get the best method from a comment on a comic. :-)

Actually, there's an even smarter way. Add the two digits and place them in the middle of the original number:
11*13=143
11*36=396
11*47=517(carry over)

Wow, I'm a math and science guy and it amazes me whenever I learn a trick like that. Math is a beautiful thing.

You are correct but only for 2 digit numbers. For numbers with more than 2 digits the method is slightly different.
234x11
2574
The way to get the first and last digit are the same but we do not add 2, 3, and 4 all together. We only add 2+3=5 and 3+4=7.

That's what I do.

What base? Decimal or hexadecimal? Can I use a calculator?

I am not a mathematician, but I sure can do arithmetic. I love this comic.

That's because Sonic Lover is a Alpha Geek.

Seriously guys?
Multiplying by eleven is easy by head, no matter what the second number is.

For you!

Well, I honestly can't add 130 + 13. You know 13 is a very scary looking number. (It is, trust me!!) heh

You guys, 11x13 = 12^2-1 = easy.

I see what you did.
You remembered that (a+b)(a-b)=a^2-b^2
And you set a equal to 12 and b equal to one
So 11 times thirteen equals twelve squared minus one which is 144-1 or 143

A fellow mathematician once told me: There are three kinds of mathematicians: those who can count and those who can't.

Given that, how do you expect us to do higher arithmetic? There's a reason I like algebra. X times Y is always XY, but who can figure out what 11 and 13 make?

Wait. Doesn't that make eight kinds of mathematicians?

11 times 13 is 1113 by bmonk logic,
Who said they were numbers?

For mathematicians.. numbers don't even exist.. they might as well be letters or drawings..

he could have said: it gives up kittens! makes no difference

wow..i cant iterate how much i can relate to this comic. i get an entire formula worked out, then in the end i do 2+3=6 or something like that

SHEESH YOU PEOPLE! 143!

Also what is it with the algebra?? this is just simple multiplying!!!

And also, PLEASE, SOMEONE TELL ME, what is the difference between Maths and arithmatic?

How to easily calculate 11*13

if x= 10
then, 11= x+1, 13= x+3
(x+1)(x+3)=(x^2+4x+3)
(10^2+4*10+3)=143

That was easy, wasn't it?

You guys missed an intro step in your High School algebra classes. You all know how to do (x+1)(x+3)

Well what about (10+1)(10+3) or 13(10+1)

Both of those are really simple to do. Come on guys.

There's a WAYYY easier way to multiply by 11:

Take the two digits of the multiplicand, add them together, and put the result in the middle!

13 x 11 ---> 1 + 3 = 4

therefore 1"4"3

works with any... 11 x 53 = 583
11 x 72 = 792

(if the sum is 10 or more, carry the one)

11 x 76 = 836 (not 7136, obviously)

See, this is why I always transform an arithmetic problem into an algebra problem, like all the comments have described. Mathematicians don't do arithmetic!

Hmmm... To be fair, I'm mathematician but I still try to keep up with arithmetics as much as possible. Not because it's related to math, but because it's friggin' handy if you can multiply and divide fast.

How come nobody paid attention to 143? 143 = love, mathematicians don't know love? :O

"Because 1... is the loneliest number!"

You know, unless it's next to zero, then it's binary, and it's never alone.

Your logic is based on the premise that that which is alone is also lonely. I use myself as a case in point to counter that claim.

Geez guys!

the answer is I Love You!
that guy let that chick slip right through his palms!

13 * 11
(12+1) * (12-1) = 12^2-1 = 144-1 = 143

To multiply 2 digit number with 11 is pretty easy.
11*XY=X?Y, where ? is sum of X and Y
f.e.
11*35=3?5=385 (?=3+5)

Of course, because of some exceptions (what if X+Y>10) you must think about overflow, which adds 1 to first number of solution:
f.e.
11*56=5?6, ?=11, =616

This "trick" known for centuries is just one of many known as Vedic mathematic.

When I get that question i have some standard answers: Use a calculator; I'm not a calculator; I'm not a mathemagician!!

11 * 13 =

13*10 = 110
+
13* 1 = _13
____________
11*13 = 143

Tens place for the win! It makes a lot of math easier.

37*42
(tens place)42*30=(42*10*3)=(420*3) = 1260
(ones place)42*7=(40*7)+(2*&)=280+14= _294

I dunno. It's much easier for me to factor down numbers and add them in my head, than doing long multiplication. Even though that's basically what multiplication is.

X-Files 3X20: "Jose Chung's From Outer Space"
http://en.wikipedia.org/wiki/Jose_Chung%27s_From_Outer_Space

"How the hell should I know?" is a running gag in that Episode!

im a math major, not a calculator.

It's "I Love you".

My guess is that arithmetic is as important for many mathematicians as handwriting is for a writer -- and for much the same reason.

I have known math majors who would disdain to answer this question, but I have not met any who could not answer it. At least some of you are posing...I hope.

i think the idea behind the comic is correct but she should ask 37x78 or something like that. 11X13 is so simple. Let me explain why the idea is correct. At adv. lvls of mat you ara working on sets and functions. open set closed set intersection of infinite sets. also functions derivatives wich contain 3 or more unkowns. So basic number calculations is meaningless for you. i dont waste my time if someone ask me what 27x34 is equal to. But you could give me a set and some addition and scalar multiplication on this set then you may ask if it is a vector space or not. if you ask a question easier then this one. i think it isnt worth to think about it ;)

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