There is a calculator in which all digits(0-9) and the basic arithmetic operators(+,-,*,/) are disabled. However other scientific functions are operational like exp, log, sin, cos, arctan, etc. The calculator currently displays a 0. Convert this first to 2 and then to 3.
Solution posted in comments by Siddhartha, Sumit, Salman Khan and Kapil Dubey. Thanks. Interesting generalisation proposed by Siddhartha.