Python variables, expressions, and data types

Match the following values with their Python data types

• str (string)

• 7.3

• bool (boolean)

• "Hello"

• float (decimal)

• True

• int (integer)

• 4

Order the below into the correct order for an assignment statement in Python. Not all options are used.

​ (a)   ​ (b)   ​ (c)  

• x
• =
• 7.3
• /
• @

What are the two (2) preferred (as opposed to valid) naming styles for variables in Python?

• Camel case

• Traditional

• Formal

• Proper

Answer explanation

Camel case (thisIsCamelCase) and traditional (this_is_traditional) are the two preferred ways to name variables.

Python, as a language, accepts all names that:

start with a letter (no numbers!) or underscore

do not contain any special characters except for underscores (_)

do not contain a space

What is the result of the following Python print statement?

print(4 + 2 * 3 - 6)

Mathematical Equivalence

ON

Answer explanation

Follow PEMDAS: parenthesis, exponents, multiplication and division, addition and subtraction.

Do 2 * 3 first (6) then addition and subtraction from left to right:

4 + 6 = 10

10 - 6 = 4

Which of the following are valid Python variable names?

• 4square

• route66

• home_address

• studentAge

• ver1.3

Answer explanation

What will this code output?

print("confusion")

• Confusion

• confusion

• Syntax Error

• print

In the following code, what is happening?

foo = "bar"

• A variable named foo is being created, with a value of "bar"

• A variable named bar is being created, with a value of "foo"

If foo is equal to 3 and x is equal to 4, what is the value of foo after this operation?

foo = foo + x

• 4

• 12

• 7

• 34

Answer explanation

When a variable is on the left side of the assignment operator (=) it is the place where the result is stored. When it is on the right side, it's value is used as part of the operation. Since foo is 3 and x is 4:

foo = foo + x

foo = 3 + 4

foo = 7

We say that 7 "overwrites" the old value of foo.

In the following code, what value will be assigned to the variable "cat"?

mouse, cat, dog = "small", "medium", "large"

• small, medium, large

• small

• medium

• large

• Nothing, that operation will throw an error

Answer explanation

As explained in the W3 Schools tutorial, when you have a list of variables and a list of values, the values are assigned in order to the variables.

Note that a list of values is NOT the same as a string of values!

foo, bar, bam = "one", "two", "three" <- this is a list of values

foo, bar, bam = "one, two, three" <- this is a string containing commas which look like a list

The second line will generate an error, as there are three variables, but only one text string.

What will the following code output?

biff = 3.4

print(biff)

• An error because 3.4 is not a string

• 3.4

• "3.4"

• 3

Answer explanation

The print() function will print any type of variable.