--- id: 5900f3ff1000cf542c50ff12 title: 'Problem 147: Rectangles in cross-hatched grids' challengeType: 5 forumTopicId: 301776 dashedName: problem-147-rectangles-in-cross-hatched-grids --- # --description-- In a 3x2 cross-hatched grid, a total of 37 different rectangles could be situated within that grid as indicated in the sketch. ways of situating different rectangles wihtin cross-hatched 3x2 grid There are 5 grids smaller than 3x2, vertical and horizontal dimensions being important, i.e. 1x1, 2x1, 3x1, 1x2 and 2x2. If each of them is cross-hatched, the following number of different rectangles could be situated within those smaller grids: $$\begin{array}{|c|c|} \hline 1 \times 1 & 1 \\\\ \hline 2 \times 1 & 4 \\\\ \hline 3 \times 1 & 8 \\\\ \hline 1 \times 2 & 4 \\\\ \hline 2 \times 2 & 18 \\\\ \hline \end{array}$$ Adding those to the 37 of the 3x2 grid, a total of 72 different rectangles could be situated within 3x2 and smaller grids. How many different rectangles could be situated within 47x43 and smaller grids? # --hints-- `crossHatchedRectangles()` should return `846910284`. ```js assert.strictEqual(crossHatchedRectangles(), 846910284); ``` # --seed-- ## --seed-contents-- ```js function crossHatchedRectangles() { return true; } crossHatchedRectangles(); ``` # --solutions-- ```js // solution required ```