Finding number of memory locations in chip
Here is an actual chip! From the '70s :

Motorola MC6810

https://upload.wikimedia.org/wikipedia/commons/f/f8/Motorola_Microcomputer_Components_1978_pg08.jpg

http://www.icpdf.com/MOTOROLA_datasheet/MCM6810_pdf_874837/#view

128 bytes : 128 * 8bits = 1024 bits = $2^{10}$ "memory cells".

I suppose the author considers each bit in a RAM as a "memory location", the way a memory is addressed, the data bus width, doesn't change its capacity : A 1Mega * 8bits RAM has the same capacity as a 512k * 16bits.

On the MC6810, there are 6 chip select inputs, but they are used to ease the selection of different chips connected in parallel, they don't add to the RAM storage capacity.