I think this assignment is so tough because it looks like a string concatenation problem and most students don't make the leap to realize that it's actually a place-value problem. I've had students write all the examples and still not get the problem.
<br><br>My first hint is, "Remember when you wrote expanded notation in elementary school?" This works for about 15% of them.<br><br>I then mention place-value and, if that doesn't work, I ask them which place each digit in the function call ends up in. Usually, at some point, they have a light-bulb moment and are kind of embarrassed. This is one that some students never "get" until you tell them, but all of them understand after they see it.
<br><br>Todd<br><br><div class="gmail_quote">On Jan 8, 2008 10:23 PM, John Clements <<a href="mailto:firstname.lastname@example.org">email@example.com</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div class="Ih2E3d"><br>On Jan 8, 2008, at 7:08 PM, William Stanley wrote:<br><br>> Exercise 2.2.4. Define the program convert3. It consumes three<br>> digits, starting with the least significant digit, followed by the
<br>> next most significant one, and so on. The program produces the<br>> corresponding number. For example, the expected value of<br>> (convert3 1 2 3)<br>> is 321. Use an algebra book to find out how such a conversion works.
<br>><br>><br>> Okay I had gone past this exercise but as I couldn't figure it out<br>> it was bugging me... and I must say its been a while since I<br>> regularly used algebra but after racking my brain for a while and
<br>> googling for even longer I throw myself at your mercy... I am sure<br>> it is rather simple but I am stumped... sometimes I wish I could<br>> peek at those answers... even just to see if I got it right.<br>
><br>><br>> Travis Stanley<br><br><br></div>I hate to be the design-recipe-bot, but... have you tried following<br>the design recipe? What are the examples you came up with? Are<br>there simple examples that you know how to do?
<br><font color="#888888"><br>John Clements<br><br></font><br>_________________________________________________<br> For list-related administrative tasks:<br> <a href="http://list.cs.brown.edu/mailman/listinfo/plt-scheme" target="_blank">