#1


Banished Join Date: Dec 2012
Posts: 14,056
BattleTag: Hulk#2393

help brain stupid slow at math. me smart. orc.
6,7⋅7,3.
help me get a "strategy"/thought process for this which i can use quickly. napkin math sure, but its been like a loooooooooong time since i did math like this. I want to do it without calculus. I know i can google it but I think i always had a problem with this. It will help me ALOT in the long run ^^ 
#2


Elune Join Date: Dec 2014
Posts: 7,261

I'm not sure I follow.

#3


Elune Join Date: Jul 2013
Location: Trickster's Mighty Keep
Posts: 7,369

And there goes Gurzog again. Slowly but surely gurzogging his way right into insanity once more!

#4


Banished Join Date: Dec 2012
Posts: 14,056
BattleTag: Hulk#2393

x.y * a.b just tell me how to solve such a simple math problem.
Its Decimal multiplication with two decimals. (one in each made up number. 
#5


Elune Join Date: Jul 2013
Location: Trickster's Mighty Keep
Posts: 7,369

Basically, you want to know how to multiply decimal numbers?
That should do it, bro. 
#6


Banished Join Date: Dec 2012
Posts: 14,056
BattleTag: Hulk#2393

without a calculator. using at most pen and paper.

#7


Elune Join Date: Nov 2013
Location: Vienna, Austria
Posts: 10,096
BattleTag: miffy#1110

__________________
El. Psy. Congroo. 
#8


Needs A Hug Join Date: Mar 2011
Location: Over the hills and far away.
Posts: 6,136

When adding or subtracting, the decimal stays in the same spot.
If the two numbers are going to turn out to be negative (small number  big number), flip them around so that it's the big#  small#. Then make your answer a negative number.
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#9


Banished Join Date: Dec 2012
Posts: 14,056
BattleTag: Hulk#2393

my problem is multiplication and division. you know 5* 5 = 25
4*4 = 16 9/3 = 3 10/2 = 5. but with decimals. 
#10


Demon Hunter Join Date: Aug 2012
Posts: 498

What am I doing with my life
6.7 x 7.3
Ignore the decimals, multiply as normal. 67 x 73 = 4891 There were two numbers after the decimal to start, so move the decimal point to keep two numbers after the decimal. 48.91 67 x 7.3 = 489.1 6.7 x 7.3 = 48.91 6.7 x .73 = 4.891 .67 x .73 = .4891 
#11


Banished Join Date: Dec 2012
Posts: 14,056
BattleTag: Hulk#2393

Thanks.

#12


ArchDruid Join Date: Sep 2013
Posts: 1,269
BattleTag: Sagara#2842

Another plan is to use a trick derivative from (a+b) * (c+d)
Goes something like that: 6.7 * 7.3 = (70.3) * (7+0.3) = (7*7) + (0.3*7) + ((0.3)*7) + (0.3*0.3) Each is easy enough to solve, and if you're attentive you can probably catch that the two middle values are going to cancel each other out: 49 + 2.1  2.1  0.09 = 49  0.09 = 48.91 It's a bit longer than Shamu's trick which I'd advise for the example, but it has two advantages for specific situations: a) It's flexible enough to be used in most complex multiplication: 49,99 * 6.5 is just as easy to solve b) If you just need to ballpark a value, even extremely complex numbers can be boiled down reasonably well: Take 4.523 * 6.712 Boil it down to 4.500 * 6.700, solve that one to 30.150.000 and you're actually within a couple of % of the actual answer (30.358.376). Technically, if you boiled it even MORE to 4.500 * 7000 you'd still be within a 5% margin. 
#13


Master Worldbuilder Join Date: Sep 2012
Location: A Dying World
Posts: 18,136

What is this, the dark ages?
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#14


Banished Join Date: Dec 2012
Posts: 14,056
BattleTag: Hulk#2393

its for a test in sweden where we use our pens and brain.

#15


Master Worldbuilder Join Date: Sep 2012
Location: A Dying World
Posts: 18,136

Your education system sucks. You're describing rote memorization, not problem solving.
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#16


Banished Join Date: Dec 2012
Posts: 14,056
BattleTag: Hulk#2393

well the test is set up in such a way the higher the score the higher the chances you get into an university of your choice.
https://en.wikipedia.org/wiki/Swedis..._Aptitude_Test its sort of like the america SAT i think, honestly i have no idea. 
#17


Join Date: Apr 2007
Location: New York
Posts: 34,378
BattleTag: Omacron#1477

... How old are you?
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#18


Banished Join Date: Dec 2012
Posts: 14,056
BattleTag: Hulk#2393

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