A computer adds and compares data primarily in the Central Processing Unit (CPU). More specifically, these operations are performed by the Arithmetic Logic Unit (ALU) , which is a core component of the CPU. The ALU executes arithmetic operations like addition and logical operations such as comparison. The CPU interprets instructions, processes data, and controls input/output devices, making it the "brain" of the computer for these tasks

. To summarize:

• Addition and comparison happen inside the CPU , within the ALU.
• The CPU fetches data and instructions from memory, processes them, and then sends results to output devices or stores them back in memory.
• Other components like memory, hard disk, or floppy disk serve as storage but do not perform arithmetic or comparison operations themselves

Thus, the CPU chip is where a computer adds and compares its data.