calculations

Press Windows + R, then type "calc" and enter. That's how you can quickly bring up the calculator application on your Windows computer. This is also the reason many of us do not need a physical calculator around as there's always a PC nearby. But if you are going to have a calculator, here's one worth getting--the 10 Key Calculator created by U.K. designer Sam Hecht, as seen on Boing Boing.

It doesn't really have only 10 keys, but this calculator looks very much like your computer's numeric keypad. You no longer have … Read more

For consistent 15 percent tipsters living in municipalities with a 7.5 percent dining tax, generating the perfect 15 percent tip is as simple as doubling the tax. If that's not you, Oh Arithmetic-Challenged One, you've got a bum deal. (See below for a quick computational technique.)

It's for this set, and for diners who frequently split a bill, that Ilium Software developed Tipster. The free, simple app for Palm, Windows Mobile smartphone and Pocket PC hurriedly computes your tax and total.

Tipster calculates tax in 5 percent increments up to 30 percent, and can evenly split … Read more

Who knew tackling global warming could be so fun?

A Boston-area entrepreneur has launched a Web site called Carbonrally that aims to marry online games and social networks with consumers' desire to shrink their carbon footprint.

Here's how it works. The company behind Carbonrally, Carbon Challenge, regularly posts a "challenge" that translates into a reduction in greenhouse gas emissions. Choosing filtered tap water over bottled water, for example, translates into reducing 3 pounds of carbon dioxide emissions a week. (No plastic bottles involved.)

Individuals or teams can take up the challenge. Typically, it's the "dark … Read more

In photography, the idea of depth of field, or the portion of a photograph that is in focus, isn't an easy one to grasp. Like almost everything else in the photographic world, it is possible to figure out what the depth of field of a given (or even hypothetical) photograph based on the size of the film or imaging sensor, focal length, aperture, and the distance to your subject. Given the number of factors involved though, the math gets a little complicated. Thankfully, the folks at ExpoImaging have created the ExpoAperture2 Depth of Field Guide to figure it all … Read more

What were we just saying about combo devices that include numeric keypads? Oh yeah, that we can't get too excited about them. Well, that goes double for this combo camera calculator.

Not only does it have substandard resolution and "all the standard functions you'd expect to find on a crappy knock-off," as put delicately by OhGizmo, but it also looks ridiculous too. As much as we understand the practical desire to combine portable functions, we've never heard of a calculator being among the most pressing needs.

Perhaps most disturbing of all is that it's … Read more

If you have ever wondered just how much to tip your server after a restaurant meal, this iPhone app is for you. Simply enter the total cost, use a five-star rating system to rate your service, then select the number of people (if you're splitting the cost). We like this app, but question whether people will pony up $1.95 for a 3-month subscription to use it. Register with Kudit to get a 15-minute free trial.

iPhone Link: http://www.kudit.com/applications/tipcalculator/

Web site link http://www.kudit.com/

Believe it or not, there are some retro gadgets that are even too old for us. So we must seize on them while we can, because soon the only machines that will fall into this category will be from the Industrial Revolution.

Enter the HP 35s calculator, a new version of the original HP-35 (note the hyphen) released in 1972, which is being trotted out from the rest home for its 35th birthday. The seminal gadget has been updated to include "ample memory for keystroke programming, equation solving and more than 800 storage registers; 100 built-in functions; and a … Read more

Ever have trouble calculating how much you should give the wait staff after that pricey meal? Tipping is easy if you have this app for the iPhone. Just enter the number of diners, the amount, and the tax on your iPhone and the tip calculator will tell you the correct amount to tip.

iPhone Link: http://dannyg.com/iphone/tipCalc/

Web site link http://dannyg.com/iphone

Tip calculators are pretty common in most cell phones, but unfortunately the iPhone only has a regular ol' calculator (Which you can also use to calculate tip, but that's beside the point). Danny Goodman has developed this neat little tip calculator for the iPhone--enter in the number of diners, the total, tax, and it'll calculate the tip for you, plus the total amount of money each diner needs to pay up. I really liked that with each tap of an empty field, a large number keypad pops up, making it easy to enter in the numbers.

iPhone link: … Read more