Creating a control group using contact ID and format data action

Morning team!
I have an interesting one I’d like to ask you guys about today, control groups. Several teams I work with use them to help track the success of campaigns, etc. Usually taking 10% who do not take part in the campaign.
Currently, the team export new contacts, divide them up into groups 0-9 (Taking the 3rd to the last digit in their contact ID), then reimporting them with their new segments. A bit of a time-waster! This should be automatable.
I feel like this should be possible through format data action in a workflow, but haven’t got there yet.
Can you guys think of a way of clipping the first/last characters from the ID to retrieve 1 digit? Maybe even dividing/rounding/etc the contact ID down into 1 digit? The end goal being an even spread of contacts across 10 control groups 0-9.

(No cheating and saying custom code action :wink:, I want the team to be able to do this without dev interaction if possible)

Steve

Hi @Stevie-Kv,

Without custom code, that would only leave an integration like Zapier, for example. Send contacts into a Google Sheet, assign a random number via a Google Sheet function, sync that number back into the contact record. This would require a one time setup but not coding from end users. You could then easily build lists of the lower and the upper half of the numbers range.

Hope this helps!