The number of input combination for a 4 input gate is ______

Each input to a logic gate can independently take one of two binary values, 0 or 1. When a gate has several inputs, the total number of possible input combinations is found by raising 2 (the number of possible values per input) to the power of the number of inputs.

For a gate with 4 inputs, the number of combinations is calculated as:

\[ 2^{4} = 2 \times 2 \times 2 \times 2 = 16 \]

So a 4-input gate has 16 possible input combinations, ranging from 0000 through to 1111 in binary.

Exam takeaway: for any logic gate, the number of input combinations is always \( 2^{n} \), where \( n \) is the number of inputs; memorise this rule rather than the specific totals for each gate.