Solution to Sudoku no 692

Sudoku no 692 (Extreme)

This puzzle is very difficult. Please add a comment below if you manage to solve it.

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Solution to Sudoku no 691

Sudoku no 691 (Diabolical)

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Solution to Sudoku no 690

Sudoku no 690 (Tough)

Our younger son created this puzzle using a Javascript program which he wrote himself. It has only two tough steps so would not have made it into my book.

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Solution to Sudoku no 689

Sudoku no 689 (Easy)

Our younger son created this puzzle using a Javascript program which he wrote himself.

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