Binary representation
Expressing numbers using base-2 positional notation with digits 0 and 1, the foundation of digital computing. Binary representation encodes all data in computers—numbers, characters, images. Converting between binary and decimal involves positional place values (2^n). Binary operations form the basis of digital logic.
Formula
Decimal = bit × 2^n (summed for each bit position)
Real World
Every photo stored on your iPhone is ultimately a sequence of billions of 0s and 1s — binary digits that represent pixel colours, which the A-series chip processes using binary arithmetic at billions of operations per second.
Exam Focus
When converting binary to decimal, write out all place values first to avoid skipping a column — a common mark-losing error.
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