Today’s Question of the Day:

How many possible first moves are there in chess?

In chess, the pieces are divided into white and black sets. Each set has 16 pieces, which includes the following:

  • 1 king: can move one square in any direction.
  • 1 queen: combines the power of the rook and bishop and can move any number of squares horizontally, vertically, or vertically, but it may not leap over other pieces.
  • 2 rooks: can move any number of squares horizontally or vertically, but may not leap over other pieces.
  • 2 bishops: can move any number of squares diagonally.
  • 2 knights: can move two squares vertically and one square horizontally, or two squares horizontally and one square vertically; it’s the only piece that can leap over other pieces.
  • 8 pawns: can move forward to the unoccupied square immediately in front or move forward two squares if it’s the first move.

The white set always moves first. Let’s look at the two pieces that can make the first move: the pawn and the knight.

Take a look at the white pawn in space a2, which can move either 1 square or 2 squares forward.

Now, take a look at the white knight in g1. Remember that the knight can move two squares vertically and one square horizontally, or two squares horizontally and one square vertically piece. This knight can then move to square f3 or h3.

Let’s put it all together by looking at all the possibilities.

  • There are 8 pawns, that can make 2 possible moves each. That adds up to 16 possible moves by the pawns.
  • There are 2 knights, that can make 2 possible moves each. That adds up to 4 possible moves by the knights.

Summing all the possible moves, we get 20 possible first moves in chess!

*Bonus question*
What is the probability that the white knight in g1 will move first?