Hash totals are used to check that groups of numbers have been input correctly.

A hash total is the sum of a group of numbers that are going to be input.

The hash total is input along with the numbers. The computer calculates a hash total for the numbers that have been input.

If the hash total calculated by the computer does not match the hash total that was input with the numbers then one or more of the numbers have either not been entered or have been entered incorrectly.