1. Start by identifying rows, columns, and 5x5 subgrids with the most filled cells to narrow down possibilities.
2. Use the standard Sudoku rule: each row, column, and 5x5 subgrid must contain all numbers from 1 to 25 exactly once.
3. For each empty cell, list possible candidates by eliminating numbers already present in its row, column, and subgrid.
4. Look for “naked singles” — cells with only one possible candidate — and fill them in.
5. Apply “hidden singles” — when a number can only go in one cell within a row, column, or subgrid — and place it.
6. Use advanced techniques like “naked pairs,” “pointing pairs,” or “box-line reduction” if basic methods stall.
7. Repeat steps 3–6 iteratively, updating candidates after each placement.
8. If stuck, try “trial and error” on cells with few candidates, backtracking if contradictions arise.
9. Continue until all 625 cells are filled without violating Sudoku rules.
10. Verify the solution by checking that every row, column, and 5x5 subgrid contains digits 1–25 exactly once.
Parent Tip: Review the logic above to help your child master the concept of printable sudoku 25x25 numbers.
