September 2007

## Mystery sum sudoku

Fill in the grid so that each row, column, and block contain the numbers 1-9 exactly once, and so that there are no repeated entries in any connected shaded region. In addition, all shaded regions of a given color add to the same sum; for example, if one red shaded region has entries that sum to 21, then all red shaded regions in that puzzle sum to 21. The sums are not given; you must determine them yourself.

This puzzle was kindly provided by Brainfreeze puzzles, a puzzle making company run by the mathematician Laura Taalman and the software developer Philip Riley, whose book Color Sudoku is available now.

## The solution

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