Why don't we use decimal in computers?

Question

Why is binary preferred in a computer system? Wouldn't it make more sense to use the more familiar decimal system instead?

Answer 1

Because binary lends itself naturally to a ON-OFF system where ON means a current and OFF means no current. Using 10 different voltage levels would be very error prone.

You could use binary numbers to represent decimal digits (this is called BCD). This has some advantages in some specific cases (like calculations using money, where a rounding error is prohibited).

Overall, the binary system wins because it is the easiest to design circuits with and the easiest to analyze and implement.