I had a neat QHC this morning when I was writing the check to pay my electricity bill. My eyes were thankfully distracted from the large dollar sum incurred through the extensive use of AC during the past month by the check number, 7272.
As I recorded the number in my check book register I wrote the check number followed by the date which turned out to be 7272 7/27 or 7272727. Not only is it a wonderful sequence but it is also a palindrome. Isn't that way cool.
The mathematical equation above is also a remarkable QHC. It's even more amazing because, as far as I know, this is the only time this happens. It's even more amazing still because the total of each side of the equation is 365, the number of days in a year.
12/12/12 was probably the greatest QHC that most of us will experience in our lifetimes. My birth-date turned out to be a neat QHC after i emigrated to the US. In the UK it was 19-12-46 which was depressingly boring and unspectacular. Now, it is 12 -19 - 46 which is really neat because sometimes I say "twelve nineteen forty six" as if it were 12-1946 and people think I have left out the day.
Here's another neat QHC. Have you ever tried multiplying a number by 9 and adding the digits in the product as in 2 x 9? It equals 18 which, if you add the 1 and 8 you get 9. Now multiply 18 by 9 and you get 162. Again, add the digits and you get 8. Just keep multiplying by 9 and the digits will always add up to 9.