Basic Sudoku techniques #2

According to the basic rules of Sudoku, every row and column must contain unique digits from 1 to 9 (cannot be repeated).

Find the digits which appear in pairs in three connected boxes
Using Sudoku basic rules, we could get some hints by finding digits in pairs, and then estimate the position for the third similar digit. This applies to three connected boxes in a row or column.
Let’s look at the below example:

There are a total of 9 boxes labeled “Box 1”, “Box 2” …

Look at Box 1, 2 and 3, both Cell F3 (Box2, Row3) and Cell H2 (Box3, Row2) have digit 7, we could estimate that the third digit 7 will be in Box 1 Row 1. So the possible cells are B1 or C1. Checking vertically down Column B, digit 7 is already in Cell B7. We could conclude that the third digit 7 is in Cell C1.

More techniques will be shared in the next post.