For calculating board feet as conveniently as possible.
The default iOS keypad is not very convenient for numeric input. Using
<input type="number"> makes it a little better, but there are still too many extra keys taking up space.
pattern="[0-9]*" gives a nice numpad, but it lacks symbols, and makes some browsers perform validation on the field. So, I made my own keypad! It has the keys needed for calculating board footage, and no more.