Punctuation and number entry

I was recently told a story by JW which made me reconsider by focus on purely digits and the decimal points. I now consider the comma to be an interesting character in the world of number entry.

J explained how he was trying to set up a monthly payment online for a particular bill.  He wanted $170.00 to be automatically taken out of his account, and sent the billing company.  On the website, he got to the text box in the form that asked for the monthly amount he wished to pay, and he entered in 170.00:

Only this isn’t what he typed. He typed this out on a laptop keyboard and so used the top row of numbers, and the full stop as a decimal place. When he typed the decimal place however, his finger slipped and what he actually entered was this:

A few weeks later, J gets a call from his wife, frantically asking him why their bank balance is so incredibly low all of a sudden. After inspection, it turns out that for two months, $17,000 has been leaving their account each month. Oops.

When J submitted the form, he didn’t notice his mistake, there was a difference of two pixels between the decimal point and comma character in the font on the web form. He saw there was something there between the first to zeros and understandably assumed it was the decimal point he’d gone to press.

The first error was typing a comma instead of a decimal point and not noticing it. But really, if this wasn’t picked up by the human, it so easily could or should have been picked up by the system. That comma is in a weird place – if it were representing a thousand marker, there should be an extra zero, or is should be between the seven and the zero. This was a malformed number entry. And the system did not pick up on this. Instead, it chose to ignore that comma, and strip it out of the input, leaving only 17000. And resulting in an incredibly angry customer.

Conclusion: Think about the erroneous characters people enter, even in number entry. Don’t ignore them without thinking about why they might be there.

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2 thoughts on “Punctuation and number entry

  1. Steve says:

    Some cultures use the comma as a decimal divider, so they may have made a “mistake”, rather than a “slip”. See, for example, German, where 170,00 is a perfectly valid number.

    • Sarah Wiseman says:

      That is a good point! When you refer to “they” do you mean the website or the person committing the error? I have to say, this incident occurred to someone from the US, on a US banking website where the comma isn’t used as a divider.

      However, this does make me wonder whether there are other incidents of people switching the comma and decimal due to cultural reasons and getting shocked with how much money they’ve suddenly spent.

      Good distinction of slip and mistake too…

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