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Hidden Pairs

Hidden pairs intro
Have a look at this grid, the third column is missing the values 2 and 6.
Both values only appear in the pencil marks for the highlighted cells. This means that there are only 2 ways we can insert 2 and 6 in this column.
Hidden pairs option 1
We can insert them this way round.
Hidden pairs option 2
Or, we can insert them this way round.
There are no other options for inserting 2 and 6 in this column, we just don't know at the moment which way round will be the solution.
Hidden pairs
This means we can remove all other pencil marks from these 2 cells.
We can remove the pencil marks 1, 3 and 5 from the top cell.
And we can remove the pencil mark 3 from the bottom cell.
Hidden pairs
This leaves us with this.
Hidden pairs
In this row, the values 6 and 8 can only appear in the highlighted cells.
We don't know which cell contains the 6, and which contains the 8, but we do know that they must be in these 2 cells.
Hidden pairs
This means we can remove all other pencil marks from these 2 cells.
Hidden pairs
To leave us with this!
Hidden pairs
In this region, the values 2 and 4 can only appear in the highlighted cells.
We don't know which cell contains the 2, and which contains the 4, but we do know that they must be in these 2 cells.
Hidden pairs
This means we can remove all other pencil marks from these 2 cells.
Hidden pairs
To leave us with this!
Hidden pairs
Can you spot the hidden pairs in this row?
Hidden pairs
Did you spot this hidden pair?
Hidden pairs
Can you spot the hidden pairs in this row?
Hidden pairs
Did you spot this hidden pair?
Hidden pairs
Can you spot the hidden pairs in this region?
Hidden pairs
Did you spot this hidden pair?
The interesting thing about hidden pairs is that after removing the pencil marks, you are always left with a naked pair. In this instance we would also be able to remove the other 9 candidate in the same column.
Hidden pairs
There are plenty of ways to move forward with this puzzle, but there is at least one set of hidden pairs in this Sudoku.
Can you spot them?
Hidden pairs
There is also a naked pair in this row, but we were looking for the hidden pair.
Did you spot them?
Hidden pairs
That's everything you need to know about hidden pairs!
Naked pairs are much easier to spot, so you should always look for them first. The next step is typically to look for hidden pairs.

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