When it comes to figuring out how much of something you will need for a given project, it can be confusing.

It might be easy to figure out the area of a room is by calculating length times width, but what about determining how many rolls of wallpaper will be needed? Let's see -- length times width of the room, converted to inches and divided by the width of the wallpaper times the length of the roll divided by 12 ... You get the point.

Why not use a calculator? Well, using a calculator can be one solution if you know how to accurately convert fractions of an inch to their decimal equivalent.

Now there is a really simple solution to all this calculating mumbo jumbo. It is a new breed of calculator -- the "fractional" calculator made especially for builders and remodelers. We used to call them "foot-inches" calculators. Fractional calculators add, subtract, multiply and divide fractions. You can actually add 3 5/8 inches together with 2 1/4 inches and get the right answer -- 5 7/8 inches.

However, builder and construction calculators are fractional calculators that take the next step.

Here is an example of a common problem associated with using a standard calculator to acquire a measurement value: Spacing the spindles in a homemade handrail system is easy. All you have to do is divide the overall length of the rail by an estimated number of spindles until you get an answer that approximates your spacing need -- not too wide, not too narrow. Sounds simple until you have to make the measurement with a decimal answer. Did you ever try finding .333334 inches on a measuring tape? Good luck!

On the other hand, with a standard fractional calculator you enter the overall length of the rail in feet and inches -- fraction of an inch included -- and divide by the approximate number of spindles desired and the answer that is fed back can be found on any measuring tape.

Building and remodeling fractional calculators take construction calculations to a whole other level of ease and simplicity. These units enlist the use of dedicated function keys to make construction specific calculations that would otherwise be difficult to perform on any kind of calculator, including the most sophisticated of fractional calculators.

For example: At the press of a button one can figure how many rolls of wallpaper, or how many yards of carpet will be needed. And the most common calculation of all -- how many gallons of paint to buy. All are light work when using the dedicated function keys on a home improvement fractional calculator.

When shopping for a construction calculator there are a few things you need to know. First, most experts agree that the less expensive models (under $25) are best suited for the do-it-yourselfer. They have fewer functions and features making them less complex to use.

Next, compare functions. Among the various features that are available:

--Basic math keys

--Fractional keys

--Board-foot key

--4x8 sheet stock key

--Paperless tape

--Fixed fraction mode

--Triangle keys

--Circle/arc keys

Each calculator offers some, but not all, of the above features. Choose the ones that are most important to you before taking the dive.

By the way, you may have some difficulty finding these babies on the Web. There doesn't seem to be any one category that you can type into a search engine that will give you a list of all the various units that are available.

Here are Web sites for several companies that make the various units and the part number that will have to be used to find the item within that site:

--www.calculated.com part #8525

--www.woodworker.com part #104-642 or part #949-811

--www.craftsman.com part #39749 or part #39785

--www.leevalley.com part #86K78.07 or part #86K78.10

You can type in fractional calculator, but you may not come up with one that is construction specific. It depends on which search engine you use.

We prefer the models that offer preset fraction keys and paperless tape. Both of these features are personal preference and neither of them is critical to the simplicity that we suggest is available with any of the units listed.

And, that's all there is to it.