We all heard how there are no such things as lucky numbers, right? Well actually… they exit!
Except there are! Here’re a few, in case you need some:
Lucky Numbers are actually a very well-defined mathematical concept*. They are simply a group of numbers sharing some properties, like Prime Numbers (a number that can be divided evenly only by 1 or itself). What’s lucky about them is essentially how they “survive” to a process of elimination similar to the one we can use to find Prime Numbers (it’s called a sieve).
And in case your date is indeed impressed by your mathematical cleverness, don’t let him/her down yet. You can further demonstrate your skills by showing how to find the first few of these lucky b***.
Write a list of integers (start with 1):
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Eliminate every second number in the list, you’ll get this:
1 3 5 7 9 11 13
The next term in the sequence is now 3, so you eliminate every third number in the list:
1 3 7 9 13
The next surviving number is 7, so every seventh remaining number is eliminated… and so on. There you go!
In a dating context, be careful not to confuse Lucky Numbers with Fortunate Numbers: They are something totally different (and actually simply named after a guy)! And well, if you are still upset that Lucky Numbers won’t bring you chance, you are out of luck: You won’t even be able to complain to the mathematician’s quartet Gardiner, Lazarus, Metropolis & Ulam who gave them that name back in 1956. None of them is still alive!
But maybe you can soothe away the pain by having a look at Happy Numbers! They are actually much more interesting in terms of properties (so far), and not really difficult to find. You start with a positive integer, like 49, and replace the number by the sum of the squares of its digits, e.g. 4^2+9^2=16+81=97, and repeat. You can, of course, start with a one digit number:
*Actually, there is TWO kinds of Lucky Numbers! We also have the Lucky Numbers of Euler. They are, however, a little less easy to play with. We define them as the positive integers n such that for all integers k with 1 ≤ k < n, the polynomial k^2 − k + n produces a prime number. And guess what: there are only 6 of them: 2, 3, 5, 11, 17 and 41. How lucky is that?