TJEx Male, 3039, Canada 67 Posts

Wednesday, November 20, 2013 10:52:55 PM Common Core will just say that if you confuse the teacher enough and BS enough you can get 2+2=5 marked correct. 

Gerry1of1 Male, 5059, Western US 33912 Posts

Wednesday, November 20, 2013 5:34:45 PM
I got stuck at '5' 

MikeyNiv Male, 1829, Europe 701 Posts

Wednesday, November 20, 2013 1:45:19 PM This is really old and not even that effective, simple long multiplication is easier 

YugureKage Female, 1829, Midwest US 1211 Posts

Wednesday, November 20, 2013 9:39:51 AM the new way kids here are being taught to multiply is just freaking strange 

Essersmith Male, 1829, Europe 275 Posts

Wednesday, November 20, 2013 9:26:46 AM @Mikeoxdbiggg Imagine quantum physics or simple integral methods. I doubt I would come up with this by my self, but this appears quite "simple". 

drawman61 Male, 5059, Europe 6548 Posts

Wednesday, November 20, 2013 8:37:54 AM @essersmith Ah, I see it now, thanks. 

Mikeoxsbiggg Male, 3039, Canada 1413 Posts

Wednesday, November 20, 2013 7:59:45 AM My question is how does someone sit down and hammer this method out? Imagine the trial and error beforehand. 

Essersmith Male, 1829, Europe 275 Posts

Wednesday, November 20, 2013 7:54:24 AM @Deyv well put. 

deyv87 Male, 1829, Midwest US 301 Posts

Wednesday, November 20, 2013 7:16:44 AM To be honest, this is good for teaching the concepts behind multiplication of multidigit numbers in a way that naturally leads to polynomial multiplication. It's just pointing out that the first one, 13*12, is equivalent to (10+3)*(10+2), then you distribute it to 10*10+10*3+10*2+3*2 which equals 156. Same for anything larger. 123*456 = (100+20+3)*(400*50*6)=(100*400 + 100*50 + 100*6 + 20*400 + 20*50 + 20*6 + 3*400 + 3*50 + 3*6)= 40000 + 5000 + 600 + 8000 + 1000 + 120 + 1200 + 150 + 18 = 56088. The concept expands to polynomial multiplication since everything so far has just been polynomial multiplication with single digit coefficients and with x=10. So if x=10, then (327*151) = (3x^2+2x+7)*(x^2+5x+1)= (3x^4 + 15x^3 + 3x^2 + 2x^3 + 10x^2 + 2x + 7x^2 + 35x + 7) = 3x^4+17x^3+20x^2+37x+7. Plugging 10 back in for x, 30000+17000+2000+370+7 = 49377. 

patchouly Male, 4049, Canada 4665 Posts

Wednesday, November 20, 2013 5:57:21 AM Slow and crude. I think the way we do it is much more efficient. 

Laran Male, 4049, Australia 435 Posts

Wednesday, November 20, 2013 5:34:22 AM This is called Vedic maths. Its actually from India.as a kid I could use this method before I learned the western method. My teachers actually graded my work as an F once because even though my answers were correct, I could not show them my working out. 

Essersmith Male, 1829, Europe 275 Posts

Wednesday, November 20, 2013 3:20:04 AM @drawman They count the number of times lines cross eachother. They go left to right, counting diagonally. So 1, 5, 6. Means that top left the lines cross 1 time. middle diagonal they cross a total of 5 times and bottom right cross 6 times. The numbers represent digits and 1's, 10's, 100's and so on. going from high to low. The 1 represent 100, 5 represent 50 and the 6 representy 6. If the lines add up to say 12. Then, given the lines location, it represents 12, 120, 1200 and/or so on. Try to apply it to the slightly larger calculation. It makes sense, in a japanese kind of way.


drawman61 Male, 5059, Europe 6548 Posts

Wednesday, November 20, 2013 2:30:17 AM So is someone going to explain? No one I always hated mathS. 

Essersmith Male, 1829, Europe 275 Posts

Wednesday, November 20, 2013 1:12:18 AM Lets try again: 996 * 693 = 690228 Less than a minute to do by "old fashion" hand calculation. This is slow aswell I suppose. About 2 minutes with the japanese system. Id love to see a japanese person do this, I presume the drawing of the system becomes less needed once you get used to it.


Essersmith Male, 1829, Europe 275 Posts

Wednesday, November 20, 2013 12:54:37 AM Crud, I miscalculated, I didnt count the blue lines!


Essersmith Male, 1829, Europe 275 Posts

Wednesday, November 20, 2013 12:51:54 AM @Nickel2 553 * 352 = 194656 I tried it the japanese way. Perhaps once you are very familiar with the system its fast. But it took me longer to sit and count and add than it took the way I was taught. 

Nickel2 Male, 5059, Europe 5458 Posts

Wednesday, November 20, 2013 12:27:52 AM The Scots are well known for being calculating...


wolfguy423 Male, 1829, Western US 172 Posts

Tuesday, November 19, 2013 11:42:35 PM this is extremely cool and easy! Ive learned this before in school. 

whirlygirl Female, 3039, Canada 230 Posts

Tuesday, November 19, 2013 10:42:10 PM I want to learn how to do this! Just... because. 

jinxiejae Female, 3039, Western US 2785 Posts

Tuesday, November 19, 2013 10:22:24 PM wait...what? what the hell are the blobs even for? I cant...I dont even...what? 

incubus_inc Male, 1829, Eastern US 976 Posts

Tuesday, November 19, 2013 9:08:46 PM geomegebra. i love it. 

Runemang Male, 3039, Midwest US 2679 Posts

Tuesday, November 19, 2013 8:46:20 PM whoa. 

Draculya Male, 4049, Asia 13365 Posts

Tuesday, November 19, 2013 8:41:12 PM We've covered this method here before 

Magentab0b Female, 3039, Western US 1462 Posts

Tuesday, November 19, 2013 8:40:50 PM I prefer long division and long multiplication when doing things by hand it's easier/quicker for me to double check. In my head I prefer weird approximations or dealing with fractions. 

drworm2002 Male, 3039, Western US 634 Posts

Tuesday, November 19, 2013 7:24:43 PM The calculator is Korean not Japanese. 
