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'Equation Sudoku' printed from http://nrich.maths.org/
by Henry Kwok
Rules of Equation Sudoku
Like the standard sudoku, this sudoku variant has two basic
- Each column, each row and each box (3x3 subgrid) must have the
numbers 1 through 9.
- No column, row or box can have two squares with the same
- The puzzle can be solved by finding the values of the 9 given
variables in the squares of the 9x9 grid. At the bottom and right
side of the 9x9 grid are numbers, each of which is the sum of a
colum or row of variables. Altogether a set of 16 equations can be
formed from the columns and rows of variables and constants.
For example, in the first and
second columns beginning from the left of the 9x9 grid, we can form
the following equations:
c + g + k = 17
f + g + a = 19
In the fourth and fifth rows
beginning from the top of the 9x9 grid, the following equations can
k + g + m + c = 23
g + p = 11
After solving all the equations, the
puzzle is solved by the usual sudoku technique and strategy.