Question

How many vacant black squares do we have in a chess board with 64 total white and black squares?

Answer 1

Here we can see there are $64(8×8)$ squares, but 4 rows are occupied with black and white pieces. So, we can say $4×8=32$ squares are occupied by the pieces and $(64-32)=32$ are empty and half of them are white and half black.

So, $\frac {32} {2} =16$ vacant black