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8 a8 k b8 c8 d8 e8 f8 g8 B h8 8
7 a7 p b7 p c7 p d7 e7 f7 g7 h7 7
6 a6 q b6 c6 d6 e6 f6 g6 h6 6
5 a5 b5 c5 d5 e5 f5 g5 h5 5
4 a4 b4 c4 d4 e4 f4 g4 h4 4
3 a3 b3 c3 d3 P e3 f3 g3 h3 3
2 a2 b2 c2 d2 e2 K f2 g2 h2 2
1 a1 b1 c1 d1 e1 f1 g1 R h1 1
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White to move

A clearance move is a move that displaces one piece so another piece can take its place. Try finding the best move for white in the following position.

Black is up 3 pawns in material, but black's king is vulnerable to back rank mate because his 7th rank pawns block his escape. If only white's bishop weren't in the way, then white could deliver mate-in-one with Rg8#. If white were to move (a clearance move) their bishop, then white could create a threat.

As a response to white's bishop move, black would push their a or b pawn to avoid checkmate. Black's queen is blocking the a-pawn, so black would be only able to push his b-pawn. White needs to find a move that prevents the movement of the b-pawn.

The solution is a pin; Bd5. White pins the b-pawn to the king, stopping it from moving. Black has to sacrifice their queen by checking white's king with Qa2+ or Qe6+, forcing white to take with bishop. Even though the sacrifice buys time and space for black to push their a-pawn, they are down 6 points of material. This will be an easy win for white.