Tuesday, 22nd March, 2016

Weird Arithmetic

Even in the age of the  computer and its old-fashioned relative, the calculator, some quirks of arithmetic are just too good to miss (to ludamus, at any rate).

Ask a friend to name their favourite digit mathsbetween 1 and 9: they may say, for instance, “6”.

Now give them the number 12345679 (that’s right – with the digit 8 missing), and tell the to multiply it by 54 (which is just 6 times 9). They can do it on a calculator, or if they’re the kind of person who likes cold showers every morning and goes about wearing a hair shirt, they can try it by hand with pencil and paper.

The answer will be 666666666.

Whatever digit they give you, just ask them to multiply 12345679 by that digit times 9: for instance, if they tell you that their favourite digit is 7, tell them to multiply by 63, which will give them 777777777, and so on.

It may be a pointless mathematical fact, or there may be a reason behind why it works which you might like to investigate. In any case, it’s fun and surprising.

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2 Comments on Weird Arithmetic »

Saturday, 10th December, 2016

Evelyn Serrell @ 11:50 pm:

This is a comment to the website creator. I discovered your Ludamus » Weird Arithmetic page by searching on Google but it was difficult to find as you were not on the front page of search results. I know you could have more visitors to your website. I have found a company which offers to dramatically improve your rankings and traffic to your website: http://dtl.la/tmJ9x I managed to get close to 500 visitors/day using their service, you could also get a lot more targeted visitors from Google than you have now. Their services brought significantly more visitors to my website. I hope this helps!

Sunday, 11th December, 2016

ludamus @ 3:54 pm:

Thanks, Evelyn, for your comments.

I’ve decided that the Ludamus site should lurk on the fringes of the web for the moment, until (and if) I get round to updating it more frequently, so I’ll pass on this idea just now, but thank you anyway.

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