Number sequences which minimise the risk of getting a valid number through a miss-key when inputted

Question

5.00/5 (1 vote)

See more:

Hi,

Soon I may be required to serialise many thousands of devices labelling them with an integer number.

The purpose of the number is to allow the device to be activated by entering the number assigned to it via an interface on a mobile phone. The process relates to real money transactions and therefore minimising the risk of accidentally activating the wrong device is essential.

I want the numbers assigned to the devices to be none sequential so going one number up or down doesn't activate another device.

The keypad is a standard numeric pad with 0 at the bottom below the number 8.

I want to minimise the risk of a single miss-key activating the wrong device.

So no single miss-key where by accidentally pressing any adjacent number key would match a valid device id. I'm happy to ignore matches where there are two miss-keys.

So I'm guessing this is more a question for the mathematicians of the group.

An example...

If a valid device ID was 12345. Where 2 and 4 are adjacent to 1, 22345 and 42345 would be excluded from the list of possible device ids.

Is there a way to generate this list using mathematical techniques or will I have to write an routine which starts with the first number, say 10000, and then work up from there testing each number in the sequence for clashes based on these rules?

Posted 6-Jul-12 2:03am

Stephen Hewison

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2012-07-06T02:45:00

Solution 1

I would change it slightly, by putting a check digit either at the start or end of the number:
If you use a (sum-of-digits plus digit-position-number) modulo 10 then your are unlikely to get the same check digit by a simple mistake. This would also protect against transposed digits: 12435 instead of 12345 for example.

Posted 6-Jul-12 2:45am

OriginalGriff

Comments

Stephen Hewison 6-Jul-12 8:48am

Excellent idea +5

Manas Bhardwaj 6-Jul-12 9:01am

v. good +5!