Bits: The Unit of Information

The bit is the smallest unit of classical information. A single bit holds exactly one of two values: 0 or 1. That is the whole story — every photo, message, and program on a classical computer is ultimately a long string of bits.

Two bits give $2^2 = 4$ combinations (00, 01, 10, 11); $n$ bits give $2^n$ combinations. This exponential growth in representable values is why bit-strings are so expressive, and it will return in a dramatic new form when we count the states of $n$ qubits.

Try it

A warm-up: how many distinct values can a single bit represent? Return the number.

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