   Killer Sudoku Help Rules / Objectives Summary

• Complete the grid such that every row, every column, and every 3 x 3 block contains the digits from 1 to 9.
• Every cage has a little clue in the corner, and digits in each cage must add to the clue.
• A digit cannot appear more than once in a cage.

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See the Basic Ideas and the Walkthrough below for extra tips and tricks, and don't forget that these are Sudoku-type puzzles, and the information in the Sudoku help might help you as well. What are the numbers for?These tell you the sums of the digits in each cage, where a cage is a collection of two or more squares inside a dotted enclosure.Move your mouse over the puzzle to see the answer. Basic Ideas • Normal Sudoku rules, tips, tricks and techniques apply. Click here for the Sudoku help page. • Every row, column, and 3 x 3 block must contain the digits 1 to 9. • The puzzle is broken down into cages, and the small number in the corner tells you the sum of the digits in a cage, 15 = 1 + 5 + 9.  • Pencil marks are the easiest way of keeping track of possible values for each square. Here we see the cage clue of 16, which can only be 7+9 or 9+7 (it can't be 8+8), so we enter both digits into the squares.  • I have provided a page that shows possible combinations to help you reduce the number possible values for some cages, for example a two square cage of 4 can only be <13> in some order. Walkthrough  Step 1This is the start of a section of a puzzle.Solve this puzzle for yourself at the same time.  Step 2A 4 cage can only be solved using 1 + 3 (as 2 + 2 isn't allowed).  Step 3There are 4 cages entirely in the 3x3 block, and these 4 cages add to 4 + 10 + 15 + 14 = 43. We know that all nine squares of a block add to 45, therefore this square is <2>. The other square in the 5 cage is therefore <3> .  Step 4These squares can't be 1 + 9 (because the <1> belongs to the 4 cage), 2 + 8 or 3 + 7 (because of the 5 cage). Therefore these squares are 4 + 6.  Step 5These squares can't be 6 + 9 (because of the 15 cage), and are therefore 7 + 8.  Step 6Therefore these square are 5 + 9.  Step 7This section will hopefully help with the rest of the puzzle.   