Vancouver is a city on the north bank of the Columbia River in the U.S. state of Washington and the county seat of Clark County.
The width of the twin quilt is 66 +12 (for the two extra columns of 9 patches) + 4 (for the two extra strips of sashing) =82, which is a bit wider than your target of 78, but close enough. Plus, it's nice to have it a bit too large than a bit too small.
King size mattress dimensions are approximately 76 inches wide by 80 inches long, making a king mattress almost the same size as two twin XL beds. This bed size is also preferable if you have children, dogs or cats that will be sharing your bed. twin size mattress is the smallest mattress available and is best suited for one child or one adult. The dimensions of a twin size mattress are approximately 39 inches wide by 74 inches long. Taller adults may be more comfortably sleeping on a twin XL bed size.