Each of the following puzzles consists of a large grid made of blue blocks and a number of stamps (the 4x4 colored grids). To solve the puzzle, fill every blue block with a pattern from one of the stamps so that the number of shaded squares in each row and column totals the number at the end of that row or column. Each stamp can be rotated, but not inverted, just like a regular rubber stamp. Be sure to fill in every blue block in each puzzle with only one stamp.

The squares already filled in the puzzle are hints to get you started; they must be filled in the completed puzzle.

Here's an example, using Stamp 1:

The solution to these puzzles comes in two forms. First, the completed puzzle is shown:

Then a detailed solution is given, which gives the reasoning behind the unique solution:

Using the only stamp available, we can fill in the block that contains the hint. The arrangement is unambiguous because the stamp has only one shaded corner square.

We can subtract the colored squares from the column numbers, leaving one square to be shaded per column in the upper left-hand corner block. Unfortunately, that leaves two possible stamp positions. Instead, we can work horizontally. By subtracting the shaded squares from the row numbers, we can determine the orientation of the stamp in the lower right-hand corner block.

Working vertically, we can deduce the stamp's orientation in the upper right-hand corner block.

Then, working horizontally, we can figure out the stamp's orientation in the upper left-hand corner.

Last updated: May 26, 2003

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