Hi Thilothama,
I think you can use the formatDecimal() to ensure that it uses the correct grouping of digits rather then toString().
https://docs.mendix.com/refguide/parse-and-format-decimal-function-calls/#3-formatdecimal
Hi Thilohama,
An an alternate way You can use Your custom logic using java by creating a Custom Java Action .
Ref: https://www.tutorialspoint.com/java_i18n/java_i18n_grouping_digits.htm
https://www.java67.com/2015/06/how-to-format-numbers-in-java.html