11.02.2006
The creation of an unique four number PIN.
The rules:
1 - Each digit by it self has to be priime. (you should know what a prime number is.)
2 - The digit place beside another digit before or next to it has to be prime. (for example: for number 789 - 8 being the number in question has to be prime, 78 has to be prime and 89 has to be prime.)
3 - The numbers cannot repeat. (for example: if you use 2 than 2 cannot be use again.)
4 - The end result PIN has to be prime.
So what did you get?
Song: "..these boots are made for walking and that's what I'll do..."
Book: GMAT; several different versions of it
Recent Purchase: H&R Block Services
Living quarters: TAC Lounge
A countdown has begun.
Comments
The one-digt prime numbers are 2, 3, 5, and 7. Since the numbers can't repeat, all four of those numbers have to be used. The first number then has to be 2 because if it followed any number, then that pairing of numbers wouldn't be prime. The number 5 can't fit anywhere else for the same reason, since no two-digit number ending in 5 is prime. So I call shenanigans, and reach for my broom.
Posted by: Rehmeyer | February 12, 2006 12:03 AM
The one-digt prime numbers are 2, 3, 5, and 7. Since the numbers can't repeat, all four of those numbers have to be used. The first number then has to be 2 because if it followed any number, then that pairing of numbers wouldn't be prime. The number 5 can't fit anywhere else for the same reason, since no two-digit number ending in 5 is prime. So I call shenanigans, and reach for my broom.
Posted by: Rehmeyer | February 12, 2006 12:04 AM
The one-digt prime numbers are 2, 3, 5, and 7. Since the numbers can't repeat, all four of those numbers have to be used. The first number then has to be 2 because if it followed any number, then that pairing of numbers wouldn't be prime. The number 5 can't fit anywhere else for the same reason, since no two-digit number ending in 5 is prime. So I call shenanigans, and reach for my broom.
Posted by: Rehmeyer | February 12, 2006 12:05 AM
Doh! Your website for some reason doesn't refresh on my web browser, so I didn't see my comment.
Posted by: Rehmeyer | February 12, 2006 12:06 AM
Hint: How about changing the order of where you put the number?
Posted by: Yin | February 12, 2006 11:34 AM
All possible 4 digit pins meeting rule no. 1:
2357, 3257, 5237, 7235,
2375, 3275, 5273, 7253,
2537, 3527, 5327, 7325,
2573, 3572, 5372, 7352,
2735, 3725, 5723, 7523,
2753, 3753, 5732, 7532.
The subset meeting rule no. 4 is:
2357, 3257, 5237, 7253,
2753, 3527, 5273, 7523.
Of those, none meet rule no. 2. In every case, the number formed from either the first two digits or the middle digits is non-prime.
I suspect either an unintentional flaw in the PIN design requirements or a missunderstanding between the customer and the PIN contractor. I suggest meetings and analysis and powerpoint. Especially powerpoint.
Posted by: Tom | February 14, 2006 09:40 AM