i have a formula field with this formula "(Update.getSuffix("toto").getPrefix("titi")).toString()"

the result is a string that looks like this "324929.222333"

if :

- i try to add the ".todecimal()" built in function to the formula the formula field doesn't show anything.

- i try to update a decimal field with the result of the formula field (with the todecimal() built in function) it doesn't work also. 

Is there any one with a solution ?

Thank you