Activity 3 - Variables

PART 1 - Command/Shell Area

In the shell area, type one at a time the following, hitting the Return/Enter key after each line. Observe the results.
```
i = 2 + 3
print(i)
i = i + 7
print("i = ", i)
```
Without running any code, what will the value of the variable n be after the following Python instructions are executed?
```
j = 5
k = 10
n = j*k
n = n+1
```
After making a prediction, run the instructions from Step 2 one at a time in the Command Area of Thonny. What value does n have at the end? How did you figure out what value n had? Was your prediction correct?
Run the command
```
int(3.2)
```
What happens? Try running the same command a few more times, each time replacing the 3.2 by some other number. What do you think int does in Python?
Run the command
```
float(7)
```
What happens? Try running the same command a few more times, each time replacing the 7 by some other number. What do you think float does in Python?

Open Thonny and create a new file called variables.py saved to the cs100/ch1 folder you created on the desktop.

In that file type the following:

i = 2 + 3
print(i)
i = i + 7
print("i = ", i)

Click the green arrow in Thonny to run the program. You’ll know it worked when something happens in the Command Area (Shell Area).
Add a line which calculates the product of 10 and 2; save it in a variable called p; then, print out the value of p with a message similar to “p is 20” (just like you did with the variable i).
Compute 2 to the power of 32. Store it in a variable called x. Print the result as “The power is: ___” , where your answer fills in the blank.

Add code that computes the average of 23, 15, 18, and 21; save that average in a variable called avg; then, display it with a message similar to “The average of these numbers is 19.25”.
Create a variable called pi with the value 3.14159. Use it to compute the area of a circle with radius 3, and print out the result.
If the universe is 15 billion years old, how many seconds old is it?

Submit your variables.py file to Activity 3 on Moodle. Make sure it runs without errors!