- A total, composed of several numbers taken from a file, which is calculated before, during, and after processing. It is calculated by adding the binary value of each character in the block. The numbers used to calculate the total do not necessarily have to be taken from numeric data. hash totals are used to verify the accuracy of processed data, or to help ensure that transmitted messages have not been tampered with. At all stages the calculated totals must match, otherwise there is an error. Also called control total.