2 Cell Chains RCB

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The Row Pairs button at the top center of the Work Grid form will open a 2nd form that displays rows with 2 or 3 occurrences of the target digit. Target digits are selected by clicking the numeric buttons at the top of the Work Grid. In this case, 2 was clicked (red background) so all the cells in the work grid that have a 2 are highlighted & in the Row Pairs form, all the rows with 2 or 3 2's are highlighted.

This makes it easy to spot possible 2-cell chains. In this case D7 & D8 have a 2-cell chain, 28 (they are the only cells in the row with 28 so either a 2 or 8 can only occur in D7 or D8). All other digits can be removed from cells D7 & D8 (37 in D7).

2 cell chains can occur in rows, columns or blocks. Row Pairs & Column Pairs assist in identifying 2 cell chains in rows or columns. Block 2-cell chains are easily identified in the work grid by using the highlighting.