Ok! These were sorta boring! 22 said “go back over everything and make sure you know it,” essentially, and because I am impatient, I went through all the previous lessons in around an hour, surprised at how much I have actually absorbed. Then I moved speed-quick over to the 23rd exercise, which says to look up code and see if you can understand it, so I did a bit of that, and now I am again quite anxious to get back to regular lessons. : )

# Monthly Archives: October 2013

# Lesson 21

Moving along, here! This lesson was mostly a refresher on function ordering, for me. At the very end, there is an extra credit portion where he recommends resolving a nested set of functions by hand before running the program.

`print "Here is a puzzle."`

```
```age = add(30, 5)

height = subtract(78, 4)

weight = multiply(90, 2)

iq = divide(100, 2)

what = add(age, subtract(height, multiply(weight, divide(iq, 2))))

`print "That becomes: ", what, "Can you do it by hand?"`

I knew that it was necessary to resolve inner parentheses before moving on to the next inner set of parentheses as just a giant composed function, but once I got to the non-commutative operations (ie, subtraction and division, in which order of operation matters) I flubbed it up a bit, and came up with a different answer than when I ran the program. Then I examined it a bit, and with a bit more analysis (that’s an overly heady word for it, ha ha!) in the form of the following:

`age = add(30, 5) #35`

height = subtract(78, 4) #74

weight = multiply(90, 2) #180

iq = divide(100, 2) #50

and then resolved the commutativity issue, I came up with the same answer that he did! woo-hoo!

Woo-hoo! Another lesson down!