Count of Days remaining from a specific date

How would you show how many days left until a certain date is reached?

It feels like an equation of

Future date - current date= days left. 

I am trying to show a countdown to a deadline on clients' projects, so every time the client record is viewed you can see this countdown.

p.s I am still trying to get the system to display a future date, where the deadline is 120 days from the client becoming a client.

 

 

This page explains what you need 

https://support.knack.com/hc/en-us/articles/115003882107-Numeric-Equation-Functions