Start the Super Simple CPU app.

Load the GCD example $($Example $6).($A blast from your mathematical past: GCD is short for "greatest common drivisor.?

Run it so youi can see that it works. $($You might want to speed it up$!$ To do this, pull down the speed list and select "fast."$)$

Click the Reset button. Click on the binary checkbox at the bottom of memory so that decimal numbers appear in memory instead of binary. In location $14,$ type $16$; in location $15,$ type $28.$ What do you think the GCD of these numbers will be$?$

Ptun the program. When it is done, take a screenshot. Find the memory cell that has the GCD and circle it$.$

What is the CCD of $30$ and $31?$ You could use the app to confirm your suspicions. Click on these buttons: Stop. Reset. Then type $"30\text{'}$ into cell $14,$ and type $-{31}^{\text{'}\text{'}}$ into cell $15.$ Press the Run button: