I think you're looking for something like this? (foldr (lambda (x y) ( + x (* y 10) )) 0 (reverse '(1 2 3)))  = 123  - inforichland <div class="gmail_quote">On Mon, Feb 16, 2009 at 7:08 PM, Thomas Chust <<a href="mailto:chust@web.de">chust@web.de</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">2009-02-16 aditya shukla <<a href="mailto:adityashukla1983@gmail.com">adityashukla1983@gmail.com</a>>: > [...] <div class="Ih2E3d">> (define guess (lambda(lsb csb msb) >         This is the part which i was not able to do , how can i combine lsb > , csb and msb so the number is of the form (msbcsblsb) .Is there any > function in scheme which can do this > >                          )) </div>> [...] Hello, there are indeed functions in Scheme that can be used do this -- they are called + and * ;-) All you need to do is multiply each digit of the number with the value of its position and add up the results. If you want to create a more general solution for an arbitrary number of digits, a function like foldr comes in handy, too. cu, Thomas -- When C++ is your hammer, every problem looks like your thumb. _________________________________________________  For list-related administrative tasks:  <a href="http://list.cs.brown.edu/mailman/listinfo/plt-scheme" target="_blank">http://list.cs.brown.edu/mailman/listinfo/plt-scheme</a> </blockquote></div>