A Simple Trick For Figuring Out the Day of the Week For Any Given Date

iStock
iStock

People typically remember anniversaries in terms of dates and years, not days of the week. If you can’t remember whether you got married on a Saturday or Sunday, or don't know which day of the week you were born on, there’s a simple arithmetic-based math trick to help you figure out sans calendar, according to It's Okay To Be Smart host Joe Hanson.

Mathematician John Conway invented the so-called Doomsday Algorithm to calculate the day of the week for any date in history. It hinges on several sets of rules, including that a handful of certain dates always share the same day of the week, no matter what year it is. (Example: April 4, June 6, August 8, October 10, December 12, and the last day of February all fall on a Wednesday in 2018.) Using this day—called an “anchor day”—among other instructions, you can figure out, step by step, the very day of the week you’re searching for.

Learn more about the Doomsday Algorithm in the video below (and if it’s still stumping you, check out It’s OK to Be Smart’s handy cheat sheet here).

The Palos Verdes Blue: The Beautiful Butterfly That Wasn't Extinct After All

U.S. Fish and Wildlife Service, Wikimedia // Public Domain
U.S. Fish and Wildlife Service, Wikimedia // Public Domain

Terrible extinction news frequently makes the headlines, but sometimes, conservationists declare defeat too early. The Palos Verdes blue (Glaucopsyche lygdamus palosverdesensis) is one such example: Presumed extinct in 1983 after it seemed to vanish from its habitat in California's Palos Verdes Peninsula, it was discovered flitting among the grass in San Pedro again 11 years later.

Aside from coming back from the edge, the butterfly is notable for fuzzy wings that look brownish when closed, but a stunning silvery blue once they open up. Today it's still listed as threatened, but there's a captive breeding program to help make sure the beautiful species never goes missing again. Learn more—and see the butterfly up-close—in the video from Great Big Story below.

Why Cutesy Names Are the Most Effective Way of Getting Your Cat's Attention

iStock
iStock

When you were naming your cat, you probably didn’t consider your feline friend’s hearing range. But according to Vancouver, Canada-based veterinarian Uri Burstyn, you probably should have—at least if you want your cat to pay attention when you talk to it.

According to Dr. Uri, the name he goes by in his adorable YouTube videos, Felix isn’t a great cat name. Nor is Garfield. But Fluffy? A great choice.

Cat ears are finely attuned to high-pitched noises. Since most of their prey communicate at high frequencies—think mouse squeaks and bird chirps—cats are not as good at hearing low-frequency sounds. Ideally, you want your cat’s name to end in a high frequency, since that’s the kind of sound cats hear best and naturally pay attention to.

For human speech, that basically means that it should end in an “eeeee” sound rather than a consonant. Grumpy Cat? A bad name. Just “Grumpy?” Perfect. That's why "kitty kitty" works pretty well to get a cat to pay attention or come toward you. It's a squeaky sound.

Luckily, many nicknames in English tend to end in an ie or a y, so you probably already have a cat-friendly name for your pet waiting in the wings. Now you know why your cat is more likely to respond to your high-pitched, baby-voiced nicknames than its full name.

Enjoy Dr. Uri's explanation, and his helpful demonstration with his noble friend Lancelot, in the video below.

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