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5 Familiar Numbers and the Logic Behind Them

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Given how digital the world has become, we are hardly bothered by having to deal with one string of numbers after the next: credit card numbers, social security numbers, IP addresses and so on. Do these numbers hold any meaning, or are they just random sequences in a database? Read on to find out.

1. Credit Card Numbers

The string of digits that make up credit card numbers have a distinct, if subtle, structure.  The first digit signifies which system it belongs to: 3 is for travel and entertainment cards like American Express, 4 is Visa, 5 is Mastercard, and 6 is Discover.  The rest of the credit card number is used differently by each company -- for Visa cards, digits 2 through 6 are a bank number, 7-12 or 7-15 are the account number, and either 13 or 16 is a check digit, a number that is the result of a  series of simple but generally secret computations with the other digits that helps verify the full number isn't fake.  In an AmEx card, digits three and four indicate the type of card and currency, 5-11 are the account number, 12-14 are the card number within the account and 15 is a check digit (AmEx card numbers are 15 instead of 16 digits).

2. Zip Codes

zipcode1Zip codes were invented by Robert Aurand Moon and by 1963 were widely used by the United States Postal Service. The five-digit number is a code for an exact location, with each successive digit indicating a more specific place. The first digit indicates a group of states; for example, a 1 directs mail to Delaware, New York, and Pennsylvania. The next two indicate a sectional center facility -- a zip code beginning with 108 directs mail to the facility New Rochelle, NY. The last two digits represent a village or town near the facility or a location within a metropolitan area. Typically in a non-metropolitan area a city gets the first area code, and surrounding villages and towns receive zip codes in alphabetical order (for example, Glenmont, NY has 12077 and Gloversville, NY has 12078). And in case you were wondering, ZIP is an acronym that stands for Zone Improvement Plan. 

3. Telephone Numbers

rotaryEveryone's a little more familiar with telephone numbers -- there's country code, necessary if dialing internationally (1 is the United States), and area codes, which indicate a broad geographic area. The next three digits indicate a smaller area, and the last four are a random permutation.  The area code and first three digits of a phone number are referred to in the telephone business as NPA-NXX.  These numbers convey a unit of purchase for telephone companies, as they will generally buy one NPA-NXX, or one combination. The ownership reveals why cell providers are often so tetchy about carrying a number from one to another, or vice versa: you would be stealing a phone number from one company and giving it to another.

4. IP Addresses

tcpip_ip_addressIP addresses, at their most basic level, identify individual computers to the Internet. They are a series of four numbers punctuated by periods that look something like 255.143.68.1. Each of these numbers (such as 255 in the example) is referred to as an octet. Each octet can have a value between 0 and 255 (so if you see an IP address with any octet higher than 255, it's fake). Together the octets of an IP address contain information about the type of network and, to an extent, the location of a computer. The first octet, called the class, tells you the size of a network a computer is in. A Class A network has a first octet between 0 and 127 and can have over 16 million IP addresses; a Class B network has a first octet between 128 and 191 and have about 65,000 addresses; a Class C network, used for most homes, has a first octet of 192-223 and can have 254 addresses. There are also Class D and E networks with first octets of 224-255 that are used for more specialized purposes. Most IP trackers use a location database to determine where an IP address is coming from, so there is not a direct scheme for the other octets. However, due to the modern use of subnetworks within a network, IP addresses are often masked. Therefore, it is no longer directly possible to tell the type of network a computer hails from.

5. Social Security Numbers

sscardSocial Security numbers are nine-digit strings that most Americans are assigned at birth, and are generally used as an identifier as well as a qualifier for various kinds of insurance and income from the government.  The first three numbers tell where the person first applied for the card; if the card was applied for at birth and the mailing address used was also the residential address, the numbers tell the rough location of birth (doesn't apply to babies born during vacation in Panama, but in general this is true).  The next two digits are called the group number, and allow SSNs of the same area number to be broken into smaller groups.  They are assigned in the following order: odd numbers 01-09, evens 10-98, evens 02-08, odds 11-99.  The last four digits, the serial numbers, are assigned consecutively 0001-9999.

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Little Baby's Ice Cream
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Food
Pizza and Cricket Cake Are Just Some of the Odd Flavors You'll Find at This Philadelphia Ice Cream Shop
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Little Baby's Ice Cream

Ice cream flavors can get pretty out-there, thanks to the growing number of creative scoop shops willing to take risks and broaden their customers’ horizons beyond chocolate, vanilla, and strawberry. Intrepid foodies can cool off with frozen treats that taste like horseradish, foie gras, and avocado, while Philadelphia's Little Baby’s Ice Cream is pushing the boundaries of taste with chilly offerings like everything bagel, Maryland BBQ, ranch, and cricket cake.

Cricket-flavored ice cream, created by Philadelphia-based Little Baby's Ice Cream
Little Baby's Ice Cream

Everything Bagel-flavored ice cream, created by Philadelphia-based Little Baby's Ice Cream
Little Baby's Ice Cream

As Lonely Planet News reports, Little Baby’s Ice Cream launched its first signature “oddball” ice cream—Earl Grey sriracha—in 2011. Since then, its rotating menu has only gotten quirkier. In addition to the aforementioned flavors, customers who swing by Little Baby’s this summer can even try pizza ice cream.

The store created the savory flavor in 2011, to celebrate neighborhood eatery Pizza Brain’s inclusion into Guinness World Records for its vast collection of pizza memorabilia. The savory, Italian-esque snack is made from ingredients like tomato, basil, oregano, salt, and garlic—and yes, it actually tastes like pizza, Little Baby’s co-owner Pete Angevine told Lonely Planet News.

Pizza-flavored ice cream, made by Philadelphia-based Little Baby's Ice Cream
Little Baby's Ice Cream

“Frequently, folks will see it on the menu and be incredulous, then be convinced to taste it, giggle, talk about how surprised they are that it really tastes just like pizza … and then order something else,” Angevine said. “That’s just fine. Just as often though, they’ll end up getting a pizza milkshake!”

Little Baby’s flagship location is in Philadelphia's East Kensington neighborhood, but customers can also sample their unconventional goods at additional outposts in West Philadelphia, Baltimore, and a pop-up stand in Washington, D.C.’s Union Market. Just make sure to bring along a sense of adventure, and to leave your preconceived notions of what ice cream should taste like at home.

[h/t Lonely Planet]

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Warby Parker
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Space
Warby Parker Is Giving Away Free Eclipse Glasses in August
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Warby Parker

When this year’s rare “all-American” total solar eclipse comes around on August 21, you’ll want to be prepared. Whether you’re chasing the eclipse to Kentucky or viewing it from your backyard, you’ll need a way to watch it safely. That means an eclipse filter over your telescope, or specially designed eclipse glasses.

For the latter, you can just show up at your nearest Warby Parker, and their eye experts will hand over a pair of eclipse glasses. The stores are giving out the free eye protectors throughout August. The company’s Nashville store is also having an eclipse party to view the celestial event on the day-of.

Get your glasses early, because you don’t want to miss out on this eclipse, which will cross the continental U.S. from Oregon to South Carolina. There are only so many total solar eclipses you’ll get to see in your lifetime, after all.

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