Monthly Archives: May 2013

Puzzle #1: International Standard Book Numbers

Some identifiers (product codes, Social Insurance Number, and on and on) have validation to detect whether a given identifier is potentially valid; some do not. The most common error in data entry is transposing two adjacent characters, and some identifiers’ validation can detect this.

Does the ten-digit ISBN (International Standard Book Number) have this type of validation?

The validation for an ISBN is as follows: Ignore the hyphens. The ten digits are from 0 to 9 except that the last digit can also be “X” for 10. Multiply the first (from the left) digit by 10, the second digit by 9, the third digit by 8, and so on to the tenth digit by 1. Add these ten products. If the result is divisible by 11, the identifier is a potentially valid ISBN—but could be unassigned—otherwise, it is not a valid ISBN.

Example: My hardcover copy of The C Programming Language / Second Edition by Brian W. Kernighan and Dennis M. Ritchie has the ISBN of 0-13-110362-8 according to the title page. 0 × 10 + 1 × 9 + 3 × 8 + 1 × 7 + 1 × 6 + 0 × 5 + 3 × 4 + 7 × 3 + 0 × 2 + 9 × 1 = 88. Since 88 is divisible by 11, this is a valid ISBN. My copy is worn, and reading the ISBN on the back cover, I could not tell what the last digit was. I thought it was a 7. Error caught!

Submit your answer to Gene Wirchenko <>. Your answer should be in the form of a proof. That means to show how your answer must be correct. The deadline is Wednesday, June 12, 2013 at noon Pacific Time. I will post the answer shortly after.

Business Miscommunication in the Job Hunt

A little courtesy can go a long way.

People looking for work are frequently advised how to go about applying. There is advice about how to put together a good resume, how one should research the company, writing a good cover letter, and on and on. Would that there were something like that for companies.

I am currently looking for work in IT so I am, once again, running into a common case of business miscommunication. About twenty years ago, I first saw companies stating on job postings that they would respond only to candidates they shortlisted. This struck me as being quite rude.

Why is it rude? Compare these two cases.

You are at dinner with friends or family. Someone next to you says, “Please pass the salad.” You pick up the salad and pass it to the person. The person says, “Thank you.”

You are looking for work. A company advertises a job opening and invites applications. You apply for the position. And usually, you will hear nothing back.

This is not very nice treatment at all.

Companies may justify it by stating how costly it is to reply to everyone. In these days of widespread use of E-mail, that just does not wash. It also has an expense. Since the expense is hidden, it may well not be considered.

They might also state that they said they would do that. So? Is something less rude because one said that one would do it? No, it is much ruder since it is obviously premeditated.

A job applicant does not exist solely when looking for work.

Suppose that I apply to Company A and do not get a response and to Company B which does reply. If someone asks me about the companies, I am not likely to mention Company A whereas I might well answer about Company B.

Company B could take advantage of the communication line to promote itself. I may well end up knowing more about Company B than Company A and having gotten some communication from them, I probably feel more favourably toward them. Maybe I or someone I know will end up being a customer or client as a result of some simple courtesy.

Another scenario is that I may have skills that do not quite match the position posted but still could be a good match for the employer. A company that does not allow for such communication is missing out.

I recently contacted a company on this basis and after a short conversation, I was told to apply anyway and that I would get a response. I submitted my application and mentioned the conversation. Later that week, I was invited to write their technical screening test. As this just happened recently, I am awaiting the results, but I might well not have had the opportunity had I not been able to talk to someone.

What if they do not hire me? Well, I will still feel that I was treated decently. That is called goodwill.

A little courtesy can go a long way.

Is This Thing On?

Hello. My name is Gene Wirchenko. I am a computer programmer / systems analyst living in Kamloops, British Columbia, Canada. I have about twenty-five years experience in the field. Being a natural analyst, I have picked apart things for years. I have been meaning to do something to pass on some of what I have learned. So this blog.

Since I find many things interesting, I will be writing about a lot of things. Some of the areas that I will write in are:

  • Computers: It could be about computers themselves, the industry, or how people deal with them. The Web can be a weird place. In the last semester of my Bachelor of Computing Science degree, I gave a presentation entitled “The Worldwide Web: An Invitation to Stupidity”.
  • Puzzles: I have been running a puzzle contest at Thompson Rivers University for about five years. Sadly, some people, when they see math or logic, turn their minds off. The subjects are not impossible to understand. It can be a lot of fun. I will be rerunning my older puzzles and running new ones when the university contest starts again in September. I urge you to give them a try. Most of them are not difficult if you use basic logic and maybe a bit of algebra.
  • Education and Learning: People learn in different ways: reading, seeing, doing, a mix. I currently tutor a high-functioning autistic boy. It is definitely a challenge to figure out how to get him to learn.
  • Blogging: Hey, I am learning. This is the second version of this blog entry. I wrote three blog entries, and somehow, the third one overwrote the other two. Even before that, just getting set up was some trouble. There is a lot of noise on the Web, but I found and highly recommend Court Tuttle’s tutorials. Go to How To Start A Blog And Get It Right. Court was also personally quite helpful to me. Kudos to you, Court.
  • Competence and Doing: Some people who are very loud about their competence are, in fact, not that competent. There is an old saw that 85% of drivers consider themselves above-average drivers. Ever wonder why this is so?
  • Games and Gaming: By “gaming”, I mean the playing of games. To me, Monopoly and its ilk are quite mundane. I do like board games though. Some board and card games that I enjoy are Carcassone, The Settlers of Catan, The Struggle for Catan, Betrayal at House on the Hill, Gloom, Groo, Girl Genius, and various crayon rail games.
  • Interpersonal Relations: How do people interact with each other? Are you someone who treats others as you like to be treated, or do you try to treat them as they would like? Extroverts can be like sandpaper to introverts. Ask me how I know.
  • Communication: This is part of interpersonal relations, but it deserves its own category. How situations have been made worse by bad communication? All too many.
  • Business: The workaday world is a large part of life.
  • What-Have-You: To be determined. You could be part of the determining. Reply or E-mail me at Gene Wirchenko <>.  If you are in the Kamloops area, maybe we could get together. I can always use more contacts and friends.

And just to make sure this blog is not a one-hit wonder, here are two more blog entries coming up fast.