Suppose that a message M = 1001 0101 1111 1000 (w₁ w₂ w₃ w₄) is transmitted using Internet Checksum (4-bit word). The objective is to compute the checksum for the message M. In order to determine the checksum, follow the steps below.

An n-bit Internet Checksum is computed as follows:

Break the stream of bits in 4-bit words w₁, w₂, ..., and w_m. For the message 1001 0101 1111 1000, list the words w₁, w₂, ..., and w_m assuming a 4-bit checksum.

Compute the 4-bit word S = w₁ + w₂, if there is a carry then set S = S + 1. Execute this step on Message M = 1001 0101 1111 1000.

3) Compute S = S + w₃, if there is a carry then set S = S + 1, Execute this step on Message 1001 0101 1111 1000.

4) Compute S = S + w_n, if there is a carry then set S = S + 1. Execute this step on Message 1001 0101 1111 1000.

Finally, the Internet Checksum = ~S (one-complement of S)