diff --git a/errata.markdown b/errata.markdown
index 106c619..b71a448 100644
--- a/errata.markdown
+++ b/errata.markdown
@@ -56,3 +56,17 @@ Suggestion:
 
 Full executable python algorithms for Chapter 9 and 10? Given the awesome pace of the early chapters I was disappointed that there wasn't any executable code in 9 and 10 :(
 
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+So you started out with a 1680 × 640 farm that needed to be split up. But now you need to split up a smaller segment, 640 × 400. If you nd the biggest box that will work for this size, that will be the biggest box that will work for the entire farm. You just reduced the problem from a 1680 × 640 farm to a 640 × 400 farm!
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+I think it's confusing as it's using W X H for 1680 x 640 but H X W for 640 x 400
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+So should it not be?
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+So you started out with a 1680 × 640 farm that needed to be split up. But now you need to split up a smaller segment, 400 × 680. If you nd the biggest box that will work for this size, that will be the biggest box that will work for the entire farm. You just reduced the problem from a 1680 × 640 farm to a 400 × 680 farm!
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