ref: 11b14a5f44967a6257ac1beabb6425f95f3b2c69
dir: /html/rect.html/
docname=rectangles:Rectangles <p> Draw lines along the grid edges to divide the grid into rectangles, so that each rectangle contains exactly one numbered square and its area is equal to the number written in that square. <p> Click and drag from one grid corner to another, or from one square centre to another, to draw a rectangle. You can also drag along a grid line to just draw a line at a time, or just click on a single grid edge to draw or erase it.