This program takes a number from memory location 2000 and performs the following algorithm on it: 
while (n > 1) {
    if (n is even)
        n := n / 2
    else
        n := 3 * n + 1
}
The program goes through the sequence 5, 16, 8, 4, 2, 1; it will halt with 1 in R0.

(This is a very interesting algorithm and I'd encourage you to write it in a high-level language of your choice, with a print statement each loop iteration, and investigate its behaviour a bit. It is an unsolved problem whether or not this algorithm terminates for all n!)

[on to problem #3]