The Check Digit and Why It’s Important

We all know the drill. Get the order right, you have a happy customer. Get it wrong? Well, the risk of brand abandonment is high, and the loss of a customer is hard to reverse. That’s why omnichannel order fulfillment accuracy is so critical. It is the keystone for the customer experience.

Validation: One of the Strategic Best Practices

Successful distribution centers (DC) have attained higher order fulfillment accuracy goals using “best practices” strategies such as process validations. A validation is a “check” built in to ensure the worker has met a condition increasing the likelihood they are about to take a correct action.

In a distribution center, validations can be applied to all processes, from inbound receiving and put away of inventory to order fulfillment, packing and shipping. A process can have more than one validation, further increasing the accuracy.

One such validation is called a check digit, a term from computer programming. Essentially, it is an additional, independent number to confirm the worker is in the correct location.

Check Digits in Action

Let’s use the order fulfillment process called “picking” or “selection” with Voxware VMS™ voice solution to provide an example.

When the worker receives an pick assignment, they are directed to the location in the DC where the item is stocked. The worker will hear this direction as a “prompt” from VMS, which is usually the aisle and location in the aisle (e.g. A 123, which is “Alpha one two three”). This is the picking location.

At the picking location, the worker validates the location by voicing the check digit (in this case, 72) of that location. An incorrect check digit will be challenged by VMS. Upon retry, if the check digit remains incorrect, the order assignment is suspended and an immediate notification sent to the supervisor.

Why Suspension can be Wise

Suspending the assignment is very important – for several reasons:

(1) The worker is prevented from making a picking error as he/she was clearly at the wrong location.

(2) Immediate notifications give responsible supervisors an opportunity to investigate the situation at the location and resolve the problem quickly.

(3) This very proactive ability to act on a problem prevents the buildup of additional problems throughout the day.

Potential Issue and Recommendation

Experienced supervisors know that a check digit can be memorized if it never changes. When a worker memorizes a check digit, he/she runs the risk of saying it before reaching the location. This sets up the possibility that the worker will pick from the wrong location upon arrival.

Voxware recommends changing the check digit schema from a single number to multiple check digits. For example, in Voxware VMS, 3 sets of numbers can be placed at the location and varied at will by the supervisor. An example:


Note the use of a different color for each set. In VMS, once the supervisor has selected the set, he/she can use the communication feature in the User Management console to advise the workers –over their headsets – what color should be used for the check digit validation. This variability reduces memorization and increases the accuracy of the picking and order fulfillment.

Stay tuned for our next blog. We’ll address additional validations, including validating by product – e.g. you might be in the right location, but the product that’s there may be incorrect. Validating by both location and product further increases the accuracy of order fulfillment, identifies inventory accuracy issues, and delivers on that happy customer!

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