a) An error-detecting scheme which is the sum of the data values transmitted. The receiver computes the sum of the received data values and compares it to the transmitted sum. If they are equal, the transmission was error-free. b) Method used to verify the integrity of data loaded into the computer. c) A simple check value of a block of data, calculated by adding all the bytes in a block. It is easily fooled by typical errors in data transmission systems, so that for most applications, a more sophisticated system such as CRC is preferred.