From a minor home repair to the construction of an entire house, virtually every construction project requires some mathematical calculations. From calculating the square footage of a room to more complicated figures like the area of a triangle or the number of board feet in a piece of lumber, a calculator and a few simple formulas are all you need. Area Measurements Measuring and calculating area takes two of the three dimensions into account: width and length, as when measuring a floor, or width and height, as when measuring a wall. For the following examples, we'll use a rectangular room that is 10' wide and 12' long and has 8' high ceilings.

* Area of the floor or ceiling: To figure the area of the room, multiply the length by the width (10' x 12' = 120 square feet).

* Area of the walls: The area of each wall would either be 80 square feet (10 x 8 = 80) or 96 square feet (12 x 8 = 96). If you need the total square footage of the walls - for figuring paint or wallpaper for example - you can simplify the calculation by adding all the wall lengths together first, then multiplying by the height (10 + 12 + 10 + 12 = 44 x 8 = 352 square feet of total wall area).

* Area in square yards: There are a total of 9 square feet in a square yard, so to calculate the number of square yards in this room, as when ordering carpet, divide the total square footage of the floor by 9 (120 square feet / 9 = 13.33 square yards).

* Area in square inches: There are 144 square inches in a square foot, so to convert an area from square feet into square inches, simply multiply by 144 (120 square feet x 144 = 17,280 square inches).

* Area of a triangle: For the area of a triangle, use this formula: .5 x the base of the triangle x the height of the triangle. If you have a triangle - a gable end for example - that is 18 feet wide at the base and six feet high from the base to the peak, the calculation would be as follows (.5 x 18 x 6 = 54 square feet).

* Area of a circle: To calculate the area of a circle, the formula is: pi x radius 2 (pi = 3.1416). So, if you want to know the area of a circle with a 22-foot diameter - which would be an 11-foot radius - the calculation would be: (3.1416 x 11 x 11 = 380.13 square feet).

* Circumference of a circle: To calculate the circumference of the same circle - the total distance around it - use the formula: pi x diameter: (3.1416 x 22 = 69.12 feet).