In this article we are going to see the function in Jmeter used for Calculations. Calculation like randomizing, incremental, simple adding etc. 

${__counter(FALSE,myVeriable)}
This is a simple counter that increments in +1.
-It uses Integer variable , so limit is 2147482647
-Counter function is fully independent 
-It has 2 parameter, First one(mandatory) take TRUE/FALSE and 2nd one is the name of Variable to store the data.
-TRUE means, it will count user separate among users
-FALSE means, the count user will be globally. All users will be counted centrally.

${__intSum(4,5,myVeriable)}
-It takes minimum 2(up to nth) integer value as variable and returns result in a variable as sum of those.

${__longSum(9999999999,22222222222,myVeriable)}
-It takes minimum 2 (up to nth) Long valueas variable and returns result in a variable as sum of those.

${__UUID}
-It returns a pseudo random type 4 Universally Unique IDentifier (UUID)
Note: I actually have not got much information about that.

${__RandomString(5,shantonu,myVeriable)}
-It returns a random string from given set of characters(second parameter) of length(first parameter which is mandatory ) and stores in a variable(third parameter)

${__Random(1,100,myVariable)}
-It returns a random integer value from given set of range (first parameter for min & second parameter for max) stores in a variable(third parameter)

Thanks..:)