You may also like

problem icon

Counting on Letters

The letters of the word ABACUS have been arranged in the shape of a triangle. How many different ways can you find to read the word ABACUS from this triangular pattern?

problem icon


What is the smallest perfect square that ends with the four digits 9009?

problem icon


Find the positive integer solutions of the equation (1+1/a)(1+1/b)(1+1/c) = 2

Equation Sudoku

Stage: 3, 4 and 5 Challenge Level: Challenge Level:1

by Henry Kwok


Rules of Equation Sudoku

Like the standard sudoku, this sudoku variant has two basic rules:
  1. Each column, each row and each box (3x3 subgrid) must have the numbers 1 through 9.
  2. No column, row or box can have two squares with the same number.
  3. 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 column 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 be formed:
k + g + m + c = 23
g + p = 11

After solving all the equations, the puzzle is solved by the usual sudoku technique and strategy.