Symmetry-Lovers, Rejoice: It's Palindrome Week!
That means the dates read the same forwards as backwards
By Neal Colgrass,  Newser Staff
Posted May 11, 2015 5:40 PM CDT

(Newser) – Ah, "kayak." Or "Was it a car or a cat I saw?" Or the date, "5.10.15." They're all palindromes—meaning they can be read the same forward as backward—and this week's dates are stock full of them, USA Today reports. In fact, palindromes run straight through from 5.10.15 to 5.19.15, as long as you write the year as a two-digit number. But if any sourpusses out there write out the month as two digits, or the year as four, the palindromes disappear, Vox notes. And they're not that rare: Every year since 2011 has had a stretch of 10 straight palindrome days, and that'll continue until 2020.

Unsurprisingly, seven-digit palindromes (like 1.10.2011) and eight-digit ones (like 01.02.2010) are more rare. Only 26 of the seven-digit kind and 12 of the eight-digit variety will come up in the 21st century, according to Aziz Inan, an engineering professor who's into the palindrome thing. "There's so much energy that comes out of these special date numbers," he says. "It keeps people interested." Meanwhile, media outlets are offering various ways to celebrate our 10-day burst of symmetry—like "taking out your friends Anna and Otto, watching a film about a world-class palindromist, or dancing a back and forth cha-cha," writes Arika Okrent at Mental Floss.