How many memory locations can a CPU with a 12 bit address bus directly address?

A 10 bit address bus can address 210, or 1024 different locations.

You can address 65,536 (216) memory addresses with a 16 bit address bus.

256

A 14 bit address can specify 214 or 16,384 different locations.

You need twenty bits of address bus to address 1024kb of memory.