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Logical mathematical reasoning/Razonamiento lógico matemático. x4

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[MAF]Agus:
Not really, using 60 from the start would just be the demonstration, but if you had no options and couldn't be able to make trial and error the way I did it gives you the right number. Adding the numbers you said gives you more than 60.

http://es.wikipedia.org/wiki/M%C3%ADnimo_com%C3%BAn_m%C3%BAltiplo

AdrenalineXV:

--- Quote from: [MAF]Agus on April 06, 2015, 03:49:34 am ---Not really, using 60 from the start would just be the demonstration, but if you had no options and couldn't be able to make trial and error the way I did it gives you the right number. Adding the numbers you said gives you more than 60.

http://es.wikipedia.org/wiki/M%C3%ADnimo_com%C3%BAn_m%C3%BAltiplo

--- End quote ---

So if it says: Pedro boasts that it is still young. If divides his age by 12, 15, 20, or 30 the remainder is 11. What is the age of Pedro?

X=LCM of [12, 15, 20, 30] + 11
12 = 2 ^ 2 * 3
15 = 3 * 5
20 = 2 ^ 2 *5
30 = 2*2*5

We take the factors with the biggest exponent, so: 2 ^ 2 * 3 * 5 = 60 -> 60 + 11 = 71.

Why do we take the LCM and not the GCD? Because of the reminder, Wikipedia says: http://en.wikipedia.org/wiki/Greatest_common_divisor

Thank you  Agus, I have got some other doubts to solve.
Regards.

[MAF]Agus:
Exactly, in your case it'd be 71.

And I'm not sure how to explain the reason why you use LCM instead of GCD :L

In this case it also has a bit of common sense, because if you had used GCD in the original problem, his age would be 2 because the GCD of those numbers is 1, and it already says that his age can be divided by 2, 3, 4, 5 and 6, and have a reminder of 1, so it wouldn't make sense

nero:
Stop doing this kids homework guys...  :police:

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