Easy Killer Sudoku is the training level for the variant. Around a third of the grid is already filled, so you can solve most of it like a normal Sudoku and use the dashed cages only as a hint: the digits inside a cage add up to its small number and never repeat.
It is ideal for beginners who know classic rules and want to see how arithmetic changes the game before the cages start doing the real work at medium and above. Learn the basics in our guide to Killer Sudoku and math variants.