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Internet QandA: How long

data crop

Internet Q&A: How many days in 100 years

Can you provide me with some good internet statistics on data use?

A lovely graphic is available and suggests Twitter users send 473,000 tweets, Spotify streams over 750,000 songs, Google runs 3,877,140 and LinkedIn gains 120 new professionals. These figures are of course, already out of date!

Data full

How many days are there in 100 years? It seems a simple enough question doesn’t it, but it’s really not that straightforward. An immediate answer, which may or may not be right, depending on the context of the question is 36,500 since a year has 365 days. That’s fine if you’re choosing a particular set of one hundred years that don’t include leap years. So if there’s a leap year every four years, that’s an extra 25 days, making 36,525.

However, that only works if you start your hundred years with a leap year, but if you don’t the number might only be 36,524. Indeed, if one of your years includes 1752, when the Julian Calendar was replaced by the Gregorian Calendar 11 days were dropped. If you prefer to work on averages, each year has 365.2422 days, making 36,524.22 days (though this depends in part on which average you’re using!) So as you can see, not as simple as might first appear. So a librarian would answer “Well it depends – which specific set of years, or what is your start year?” The answer is most certainly not 36,500, except under very specific circumstances. Let’s see how search engines handle this.

If we ask the question “How many days in 100 years?” Google gives us a quick reference answer of 36,500, which I would contend is clearly wrong. However, this column isn’t Google bashing in particular, since Bing also immediately proffers us 36,500 days as well. Yandex fairs slightly better – since it doesn’t give us a quick reference answer we can look at the first result, from with actually goes into the same kind of detail that I did in the last paragraph. Gigablast doesn’t help us at all since the first answer focuses on “a language dies every how many days?” Given that we’re not doing too well so far, I went to WolframAlpha, which is my usual go to tool for this kind of thing. Disappointingly, it also simply converts 100 years to days and provides us with 36,500 days.

You may argue that my question is flawed, and I should be asking “how many days in a century?” since at least that way we are looking at a much more specific period of time than simply 100 years which may have been chosen at random.

However, asking “how many days in a century?”, Google still gives me 36,500, as does Bing. Yandex again gives us an accurate response using, Gigablast continues to go off the rails by talking about a century of highway zombies, and Wolfram Alpha slightly redeems itself by giving us 36,524.


It’s only when I ask “how many days in a century including leap years?” does Google start to get its act together with the first result (at least for me) from Nasa, although it’s working on a different average of 365+97/400 = 365.2425. Bing pulls a result from Wikipedia which gives us the formula to work out an answer, Gigablast blows up completely and starts talking about next year’s baseball schedule and WolframAlpha throws in the towel and simply states that it doesn’t understand the query.

In summary, I may be going out on a slight limb here, but the search engines I tried are pretty useless for something like this, which is admittedly a nuanced question, but only just. If in doubt – as we all know – ask a librarian! Hopefully this will be of use if you’re running a training course!

Site of the month

This is actually a TED talk, “Fake videos of real people and how to spot them”. It’s only seven minutes long, but worth watching, if only to appreciate how scary the future is!


Contributor: Phil Bradley is an internet consultant, trainer, web designer and author.

Published: 13 September 2018

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