Binary Representation

When you see a number like $13$, its binary representation is $1101$. Reading from right to left, the positions represent $2^0, 2^1, 2^2, 2^3$, and so on.

For $1101$: position 0 has a 1 (worth $2^0 = 1$), position 1 has a 0 (worth 0), position 2 has a 1 (worth $2^2 = 4$), position 3 has a 1 (worth $2^3 = 8$). Total: $8 + 4 + 1 = 13$.

I number bit positions starting from 0 on the right. The rightmost bit is position 0, also called the least significant bit (LSB). The leftmost bit is the most significant bit (MSB).