Android Question Which string functions are supported in B4A

I really want to avoid using string functions to keep code fast.
What string functions are native in B4A?
I have found .IndexOf to be very useful, but what others are there?

I have a string with a number, say 89, I want to convert this to a 3 digit string with leading zero's, but dont know how?? please help.

In VB6 I would have simply used:
StringResult=right$(("000" & StartString),3)

in B4A I am at a total loss and I cannot find any useful info. on native string functions..