What do you know about ISBN? I know a cool trick! Try it!

[gopunk]

okay so it's 10 digits right? x means 10 btw. so you take each digit, multiply it by the place it is and sum them all up (so for example if the number was x987654321, you would go 10 * 1 + 9 *2 + 8 * 3 and so on). you take the sum of all these numbers (not my example though), and it will be divisible by 11!

try it! just grab a book!




and yes, i know this isn't really a trick, as it is supposed to be this way.

 

[Pepsi90919]

cool but what the hell's the point

 

[transluko]

like thats gonna happen. i believe you if i don't have to do it.

 

[gopunk]

Originally posted by: Pepsi90919
cool but what the hell's the point

the last digit is determined in a fashion that makes it always this way. apparently it is some sort of "check" the book people use to make sure the first 9 digits (which actually contain useful info) are correct. i'm not exactly clear on how that all works though.

 

[WW]

it's part of the standard...to catch all single digit errors and transpositions (which would be generate a faulty code and the system could respond immediately)...

 

[WW]

a technical description

 

[bmacd]

rats, i saw "ISBN" in the title and thought it was abbreviated for lesbian.
j/k...interesting trick. Just as cool as using the number "9" to multiply with.
For example:
9x9=81. 8+1=9
9x5=45. 4+5=9
and so on...

-=bmacd=-

 

[gopunk]

Originally posted by: bmacd
rats, i saw "ISBN" in the title and thought it was abbreviated for lesbian.
j/k...interesting trick. Just as cool as using the number "9" to multiply with.
For example:
9x9=81. 8+1=9
9x5=45. 4+5=9
and so on...

-=bmacd=-

another cool one is you can tell if a number is divisible by 3 if the digits add up to something that is divisble by 3. so for example, 102 is divisible by 3 because 1 + 2 = 3.

 

[amnesiac]

UPC's also have a checksum digit, but a lot more complex process of figuring it out.
Cool thing is, sometimes you can use a marker to change a digit or two and get it to scan as a completely different item. Not that I'd advocate that, of course.

 

[gopunk]

Originally posted by: amnesiac 2.0
UPC's also have a checksum digit, but a lot more complex process of figuring it out.
Cool thing is, sometimes you can use a marker to change a digit or two and get it to scan as a completely different item. Not that I'd advocate that, of course.

you better hope it's not a more expensive one