There is no theoretical reason why one could not build a "decimal" computer, but computers use binary representation for reasons of reliability.

Question

Quizplus · Accepted Answer

Computers use binary representation because it is easier to build and maintain reliable electronic components that can distinguish between two distinct states (on/off or high/low) than it is to reliably differentiate between 10 distinct states (0-9) required for decimal representation. Therefore, while it is possible to build a decimal computer, it would not be as practical or reliable as a binary computer.

There Is No Theoretical Reason Why One Could Not Build