Construction calculators solve repetitive problems. They save time. They save frustration. They save money.

Step 1:

Every wall of wainscoting has an unequal number of panels and stiles. That’s because you have to start with a stile and you have to end with a stile. So make the math easier by subtracting the last stile from the overall length of the wall.

If the wall measures 96 in., and the stiles are 3 in. wide, use 93 in. as the working length.

Step 2:

Next, choose a panel size that seems appropriate for the room—say 10 in., then add the stile width to arrive at a unit measurement for both the stile and the panel. In this case, 10 in. + 3 in. =  13 in., which is the unit measurement.

Step 3:

Divide the working length of the wall by the unit measurement. On a construction calculator, enter 93 and press the Inch key. Now press Memory +. That way you can use the number again without having to enter it again! And you’ll need to use it again.

Step 4:

Press the ÷ (divide) key and enter 13 in. (remember, enter “13” and press the Inch key). Then press the = key. The result will be 7 1/8 in. You’ll almost always end up with an uneven fractional number the first time you divide the working length by the unit size. That’s because the panel width must be adjusted slightly to fit the length of the wall.

Step 5:

To adjust the panel width, round that fractional quotient to the nearest whole number—in this case, divide 93 in. by 7. To make it easier and quicker, this time, instead of entering 93 in., press the Rcl button (Recall) and then the M+ button.

Step 6:

Next, press the ÷ (divide) key, enter 7; finally, press the = key. The result will be 13 5/16 in. That’s the location of the second stile—the first stile from the corner.

Step 7:

To lay out the third stile, simply press the + button once, then press the = button.

Step 8:

For the fourth stile, and all the others, do not press the + button! Just press the = button—over and over again.

Step 9:

The calculator will continue to add the decimal fraction to itself (13.28571), each time rounding off to the nearest 1/16 in. The panel sizes will be within 1/32 in. of each other.