A few Quick computational questions:
Show steps to compute the four-bit checksum for the message 1110 1010 0110 1010 1001. Remember to take the 1's and 2's complement at the end. Write out the message that is transmitted with the checksum.
Show steps to compute four bit CRC for the message 1011 1011 1101 1010 1111 using the polynomial x4 + x3 + x2 + 1. Write out the message that is transmitted with the CRC bits.