Originally Posted by 22B
For example, what if you want to write a program to find the GCD of two positive integers (in terms of arithmetic operations and inequalities, not just using a pre-made GCD subroutine). Is Scratch good for that?
It can do it. There is a Scratch program to compute the GCD at http://scratch.mit.edu/projects/1518558/ , where the "See inside" button leads you to the code. At age 10 my son wrote a Scratch program to find prime numbers.