See the pattern step by step
Board example
The middle 1 touches a known mine at the top left, marked with a flag. The top-right square is covered. Every other square around the 1 is open and safe.
Before
After
Why it works
The top-left mine is the one mine that the 1 counts. A mine at the top right would make two. So the top-right square is safe to open.
The rule
Use the numbers to find all the mines counted by one number. Once they are all known, its other nearby squares are safe to open.
What to check
Check the corners around the number too. Use the numbers to check each flagged mine. When the flag count matches an open number, clicking it opens its other covered neighbors. This is called chording. A wrong flag can cause you to open a mine.
Open nearby squares with one click
In the three-frame example, the lower-left 1 proves that A at the top left has a mine. Flag A with a right-click, Shift-click, or a long press on a touchscreen. The lower-middle 2 now touches two known mines with flags. Click that lower-middle 2 to open B at the top right. B shows 1. Opening a number’s other neighbors this way is called chording. Check that each flag marks a mine proved by the numbers.
Try this pattern
Use the numbers to choose your next move. Include the corners when you count. Squares outside the picture are open. Each flag marks a known mine.
Select every square you can prove safe.
See why
The top-left mine is the one mine that the 1 counts. A mine at the top right would make two. So the top-right square is safe to open.
