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# Speakers Corner

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# How good is your maths

bumpkin
Resolved

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I was asked if I had a HDMI cable which I do but they are not all the same obviously. I use HMDI as an example,the same applies to any connector.Here comes the maths bit. If there are connectors, one big and one small, one male and one female how many cables would be needed to satisfy any situation without inter connection or adapters. Long time since I studied maths but I make it 27,how about you? Now introduce a medium size and then what is the answer. Just a fun question. There is no doubt a formula for this sort of thing if anyone can remind me.

chub_tor

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BRYNIT You missed out Large Male to Large Female L/M - L/F in your notation which takes it up to 10.

bumpkin

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I got 9 the first time then cubed it hence the stupid 27.

bumpkin

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Answers so far 27, 16, 10, 9, 6.

hastelloy

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At 12.42am bumpkin clarified his question as "My point is how many ways are there for pairing 2 from 4 options."

So you only have 4 options and you have to use 2 of them at a time.

bumpkin

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Perhaps my "clarification" was not so clarifying after all, I may have worded it badly but the original post should make it clear what I meant, if not then my fault for not explaining properly.

spider9

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bumpkin

So, are you accepting the answers, 10 for the original and 21 for the introduction of the mediums?

bumpkin

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Yes, seems right to me.

hastelloy

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If we are talking mathematically and you allow like to like connections, then you must have 2 of each kind (otherwis you can't connect like to like 'cos you don't have them). This makes 8 options not 4 and 2 from 8 is 28 (Pascal's triangle).

However, if we are talking practically, the OP said "without adaptors" and I don't think it's possible to connect male to male or female to female without an adaptor so like to like connection is not possible.

hastelloy

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Incidentally - add medium and it makes 12 choices - 2 from 12 is 66.

chub_tor

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marvin42 I read the original post about "without adaptors" as a reference to the length (which bumpkin has admitted is a bit of a red herring).

Think of it this way; two pieces of kit need to be connected together. Each piece of kit might have either a Small or a Large connector either of which might be either Male or Female. To cover these combinations you would need 10 different pieces of cable with the selection of Large, Small, Male and Female.

I have no knowledge of Pascal's Triangle but if you do it empirically and write the combinations down on a piece of paper and remember (which is what I forgot at the beginning) that a cable for example with a Large Female at one end and a Small female a the other is exactly the same as a Small Female with a Large Female. Then you get 10 combinations that will join together any two pieces of kit that you have.

But Wiz-king is right, according to Murphy's Law you still won't have the one that you want in your tool box.