I have an isometric grid notebook, so I want to set up a grid of equilateral triangles, each one half m. km^2, one million km^2 for a diamond quad of two equilateral triangles. So an equilateral diamond quad is the fourth root of 4/3, (4/3)^1/4, bigger than an equilateral triangle a thousand km on a side, so 1,074.57 km wide and 930.6 km tall. Earth is 37.224 quads wide and 21.49 quads high... The actual arrangement rounds down so that the actual areas are a little more; the idea is at least a million km^2, although the comparable area in Barnes' article is more like two thirds, so an Earth equivalent would be 40 diamond quads wide at 1,000 km and 100 km/pixel, and 23.09 rows 8.6 pixels tall.