## Thinking Mathematically (6th Edition)

$13$
The expanded form of $1101_{\text{two}}$ is: $=(1 \times 2^3) + (1\times 2^2)+(0 \times 2^1) + (1 \times 1) \\=(1\times 8) + (1 \times 4)+0 + 1 \\=8 +4 + 1 \\=13$