The coordinate grid is 96 x 96. This means that there are 96*96=96^2 squares . In order to find the number of bits we should solve the problem: 2^X>96^2
2^X>=9216
We should solve the problem by testing several options:
2^10=1024 <9216 so we need more than 10 bits to encode a coordinate in that space
2^12=4096 <9216 so we need more than 12 bits to encode a coordinate in that space
2^14=16384 > 9216 so we need minimum 14 bits to encode a coordinate in that space
