Brain Warmup Department: Keen
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For those of you who used to like the puzzles I printed in the old bulletins, here is a link to an online version: one of the puzzles that I used to feature in the old paper Bulletins, but it is easy to play on a computer as well. Not so easy on a tablet or phone, since most of the puzzles require right-clicks, not easily done in a tablet or phone environment. Keen is a Sudoku variant with a little math involved. Like Sudoku, you must fit numbers into the grid (from 1 to the number of cells in a row or column) so that there are no repeats in a row or column. As well, you must ensure that the numbers placed into each block (those groups of cells bounded by heavy lines) match the number and the arithmetic operation at the top left of the block. Subtraction (−) and division (÷) are always two cell blocks and the numbers can be in any order. Addition (+) and Multiplication (×) can be three or four or more cells and some of the products can be surprisingly high! In larger blocks it is permissible to have a number duplicated as long as the duplicates are not in the same row or column. Click on the puzzle you want to try at the right (or the caption below) to go to the page with all the instructions you'll need. These puzzles come from Simon Tatham's Portable Puzzle Collection (see below) and there are links there to apps for most devices. You can make puzzles of any size and difficulty level! 
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 Easy puzzle (McBruce's time: 2min 47sec) |
 Medium puzzle (McBruce's time: 5min 4sec) |
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 Tricky puzzle (McBruce's time: 14min 50sec) |