Shiplap row math — wall height ÷ coverage width, rounded up, and the last-row rip

What this diagram shows

A 12-foot-long, 8-foot-tall wall elevation striped into shiplap rows, worked in three steps. Step one: 96 inches of wall height divided by the 4-5/8-inch coverage of a nickel-gap 1×6 gives 20.8, rounded up to 21 rows. Step two: 21 rows times the 12-foot wall length is 252 lineal feet before waste. Step three: the last row rips to 96 minus 20 times 4.625, or 3-1/2 inches, shown highlighted at the top of the wall. A green tip says to split the difference — rip the first and last rows to about 4 inches each instead of leaving a sliver, and never rip below 2 inches. The formula band reads: rows equal wall height divided by coverage rounded up, lineal feet equal rows times wall length, then add 10 to 15 percent waste.