Numbers, Math, and Times
Websites Selected by Librarians
- Calculators Online - Martindale's Reference Desk links for online calculators by subject. contains links to 1500 calculators including recipe conversions, clothing sizes, carat weight etc.
- Changing Value of a Dollar Our inflation calculator will tell you the relative buying power of a dollar in the United States between any two years from 1914-2009.
- Current Value of Old Money
- Date and Time Gateway arranged by world region and city
- Daylight Saving Time
- Financial Planning Calculators
- How far is it? This service uses data from the US Census and a supplementary list of cities around the world to find the latitude and longitude of two places, and then calculates the distance between them (as the crow flies). It also provides a map showing the two places, using the Xerox PARC Map Server
- Khan Academy video explanations of math, science, finance and history
- Lee's Useless Decimal to Roman Numeral Converter enter a decimal from 1-3999 to generate the number in Roman Numeral format
- Math Worksheet For people of a certain age, the phrase “math worksheet” may conjure images of pieces of paper with wet purple ink, freshly mimeographed. For others, they might just say: “What’s a mimeograph?” Both groups will find things to like about this website
- OnlineConversion.com Convert just about anything to anything else. Over 5,000 units, and 50,000 conversions.
- Perpetual Calendar
- Sample Size Calculator use it to determine how many people you need to interview in order to get results that reflect the target population as precisely as needed. You can also find the level of precision you have in an existing sample
- Social Security Number Allocations need to know which area the first three numbers of a Social Security number indicates?
- Sunrise/Sunset/Twilight and Moonrise/Moonset/Phase Also includes moon illuminations and eclipses. Updates every four hours.
- Time Service Dept U.S. Naval Observatory
- Time Zone Converter