Filtering the first 7 positions of an Account Name

I developed a report in Zoho Reports that is supposed to show what Accounts have not had an Event, Task or Call in the past year. All looked good until I saw some anomalies that I was able to track down to the way accounts were entered. In our system, "official" Accounts start with a 6-digit number, followed by a space, then the account name. If the sales team happens upon a new customer, we allow them to add the name to capture any notes/information and instruct them to establish an official account. These "unofficial" accounts do not start with the 6-digit number. Examples are shown below:

138114 AXCESS MFG

138376 BGK FINISHING SYSTEMS, INC.

AMERICAN MIDWEST POWER

As with any sales organization, many follow the rules, while others do not. The "unofficial" accounts are skewing the results of the report. What I would like to do is filter out any account that does not begin with a number, but I could not find a way to do that. Could anybody help?

Any help is appreciated.

Thank you!

John Galich