Add thousand separator using regex

[simon]

How can I add a thousand separator (comma's) to a number that's in a string field using regex?

e.g. 112982 -> 112,982 

[MarqueeCrew]

I think that I was in the same Coma as you @GarthM

[rs6833]

Am I missing something?  The commas are not showing with the formal applied.  ToString([Sum_dr_total],0 ,1)

[ivoller]

@rs6833, I can't recreate that. Can you check that [Sum_dr_total] is numeric before entering the formula?

[Bozhena]

Works perfect. Thanks for sharing the solution!