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'Seasonal Twin Sudokus' printed from http://nrich.maths.org/
by Henry Kwok
Rules of Seasonal Twin Sudokus
Each row, each column and each of the nine 3x3 boxes in Twin A and
Twin B contains the 9 elements - a total of 10 letters in Twin A
and all the nine different numbers 1 to 9 in Twin B.
This version of Sudoku consists of a pair of linked standard Sudoku
puzzles, with some letters and digits as starters in twin A and
twin B respectively. To get a complete solution for the twin
puzzles, we have to solve each twin puzzle with the usual
strategies but we can only get the complete solution for the twin
puzzles by substituting the corresponding element of each cell from
one twin Sudoku into the other.
So, for example we can see that in (9,1), that is row 9 column 1,
Twin A contains the letter A and Twin B contains the number 9. This
means that everywhere a letter A appears in twin A - a 9 appears in
the corresponding position in twin B and vice versa.
This immediately generates some more elements in the cells of each
Note that (4,3) in Twin A contains two letters (CH) instead of one.
This is a deviation from the regular Wordoku which contains only
one letter per square. This is the only way to squeeze more than 9
required letters into the 9x9 grid of Twin A to form two hidden
Can you guess or spot the two hidden words in Twin A?