Letter Killer Sudoku (Daily Sudoku League #70)

Most of the Sudoku puzzles which I am posting recently, I created to practice for one or another Sudoku Championship. Again this Letter Killer Sudoku puzzle is no exception. Letter Killer Sudoku appeared in the Italian round of the Sudoku Grand Prix Championship 2013. That was the first time I saw this puzzle and to practice this type I created this Sudoku. Even though this was created long back in my notebook but I took time to create the graphic image was this Sudoku.
This Letter Killer Sudoku is not a very tough one but definitely it involves doing Mathematical calculations and solving Sudoku simultaneously. I am posting this Letter Killer Sudoku as my 70th contribution to The League of Extraordinary Ladies and Gentlemen. Can you solve this Letter Killer Sudoku puzzle?

Rules of Letter Killer Sudoku

Classic Sudoku Rules apply. Additionally, the sum of the digits within each cage (dotted subarea) equals the number represented by the letter or group of letters given in the top left corner of that subarea. No digit can repeat in each subarea. Each letter A through I corresponds to a different digit 1 through 9.