Sum was chosen by Time magazine for their Summer Reading list, and selected as Book of the Week by both The Guardian and The Week. In September 2009, Sum was ranked by Amazon as the #2 bestselling book in the United Kingdom. Sum was named a Book of the Year by Barnes and Noble, The Chicago Tribune, The Guardian, and The Scotsman.
Sum's popularity led to its inclusion on Time magazine's Summer Reading list, selection as Book of the Week by The Guardian and The Week, and ranking as the #2 bestselling book in the UK in September 2009. It was also recognized as a Book of the Year by Barnes & Noble, The Chicago Tribune, The Guardian, and The Scotsman.