5: Blown apart

Explain xkcd: It's 'cause you're dumb.
Revision as of 20:26, 27 December 2013 by 108.162.231.36 (talk) (Explanation)
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Blown apart
Blown into prime factors
Title text: Blown into prime factors

Explanation

The title text explains the comic. An anthropomorphic number 70 is blown into its prime factors (2, 5 and 7). Prime numbers are numbers which can not be divided by any number other than itself and 1. Factors of a number are numbers which can be multiplied together to produce that number (2x5x7 = 70). 70 has other factors, including 1, 10, 14, 35 and 70, but 2, 5 and 7 are the only factors which are prime. All other factors of 70 (other than 1) can be formed by multiplying two of the prime factors together. Additionally, 70 is the exact product of 2, 5 and 7.

Transcript

[A black number 70 sees a red package.]
70: hey, a package!
[The package explodes with a BOOM and an brown cloud of smoke.]
[There are a red 7, a green 5 and a blue 2 lying near a scorched mark on the floor.]


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Discussion

No 70s were harmed in the making of this comic. Davidy22[talk] 14:06, 8 January 2013 (UTC)

Also, the 70 is black, and, in a subtractive colour system, black = red+green+blue. 108.162.216.85 19:14, 30 September 2015 (UTC)

... or rather black = magenta+yellow+cyan (red, green, blue are used in additive colour system), I suppose. Then again, who has magenta, yellow, cyan pens available during a boring lecture? Hagman (talk) 22:26, 2 November 2015 (UTC)
No it is the subtractive color system that is refereed as the additive ends up white. But true about the colors, but when mixing the primary colors magenta+yellow+cyan two by two you get red, green, blue, which would then in that system also mix to black! Have added this to the explanation. So thanks to both of you. --Kynde (talk) 18:18, 3 August 2016 (UTC)

I always read the factors and as 7, 5, and N. Then I realize N must be 2, and finally that it's literally 2. 162.158.222.94 (talk) (please sign your comments with ~~~~)

I think it's worth keeping the message around that was just edited in and then out again: The bomb is PRIMED, that may be the reason why it makes PRIME numbers. Fabian42 (talk) 19:03, 14 June 2018 (UTC)

Thanks for your critics but that sentence explains nothing. There is no bomb mentioned in the comic, it's an exploding package. And was it drunken, prepared, armed (obviously it was), or a mathematic variable like x' (x primed) referring to the prime symbol. You can find even more meanings of this simple word. I also don't understand why it should be the reason. Bombs are often armed but they don't produce prime factors on detonation. The explanation should be no puzzle game. --Dgbrt (talk) 19:53, 14 June 2018 (UTC)

"70 has other factors, including 1, 10, 14, 35, and 70, but 2, 5, and 7 are the only factors that are prime. All other factors of 70 can be formed by choosing zero, two, or three of the prime factors and multiplying them together." This is incorrect. You can not multiply zero, two, or three of the prime factors to obtain 1. Nitpicking (talk) 02:33, 25 November 2021 (UTC)

Usually in math, we consider the empty product to be equal to 1 because multiplying by 1 does nothing and adding zero factors to a product does nothing as well. So in this interpretation we obtain 1 by multiply zero of the prime factors. I opt for keeping the text the way it is. --Flukx 23:35 30 Nov 2022