Variables allow storing and reusing data in memory. They come in different types like strings, integers, and floats. Variables are declared, initialized by assigning a starting value, and can be reassigned new values. Programming statements are complete actions made up of expressions like initializing or assigning variables, mathematical equations, or conditionals.

1. Variables and Statements

2. Variables
• A variable is a name that represents a value stored in the
computer’s memory.
• So far, applications that you have created have stored data only
in component properties.
• Variables are objects that can save data
temporarily to reuse & simplify code.
• Variable names should be descriptive of what
they are storing
• Variables allow to update and modify code more
efficiently

3. Variable Types
• Programming languages have a plethora of variable types, however…
• Scripting languages like Python have tried to streamline
these types to the bare bones essential categories.
• There is a default variable type in scripting languages,
string.
• However Python is smart enough to know what
information is stored in a variable and knows behaviors
associated with it. That way if you store a number in a
variable it will automatically convert it for you to that type.
• Question: What are some other types of data that we could store?

4. Declaring, Initializing & Assigning Variables
• Declaring a Variable : N/A in python
• Initializing a Variable : Creating a variable and setting a
starting value to a variable.
• Assigning/Reassigning a Variable : When we set a value to a
variable

5. Creating a Programming Statement
• A programming statement is a complete action comprised of
expressions.
• A mathematical equation
• Initializing a variable
• Assigning a variable to an LED
• Ex. red = LED(17)
• name = “Jason”
• age = 34
• lie = True
• money = math.floor(1.92)

6. Variable Output
• Question: What is the difference between this and printing strings?

7. Arithmetic Operators
Name Meaning Example Result
+ Addition 34 + 1 35
- Subtraction 34.0 – 0.1 33.9
* Multiplication 300 * 30 9000
/ Float Division 1 / 2 0.5
// Integer Division 1 // 2 0
** Exponentiation 4 ** 0.5 2.0
% Remainder 20 % 3 2

8. The Power of Remainders
• Question: What is the minimum number of coins to make $.97,
how did you come to this conclusion?
Saturday is the 6th
day in a week
A week has 7 days
After 10 days
The 2nd
day in a week is Tuesday
(6 + 10) % 7 is 2
124
3
12
0
73
2
6
1
268
3
24
2 Remainder
Quotient
2013
1
13
7
DividendDivisor

9. Arithmetic Expressions and Statements
is translated to
(3+4*x)/5 – 10*(y-5)*(a+b+c)/x + 9*(4/x + (9+x)/y)
)
94
(9
))(5(10
5
43
y
x
xx
cbayx 





10. Built in Math Functions
>>> max(2, 3, 4) # Returns a maximum number
4
>>> min(2, 3, 4) # Returns a minimum number
2
>>> round(3.51) # Rounds to its nearest integer
4
>>> round(3.4) # Rounds to its nearest integer
3
>>> abs(-3) # Returns the absolute value
3
>>> pow(2, 3) # Same as 2 ** 3
8

11. The Math Module
Function Description Example
fabs(x) Returns the absolute value of the argument. fabs(-2) is 2
ceil(x) Rounds x up to its nearest integer and ceil(2.1) is 3
returns this integer. ceil(-2.1) is -2
floor(x) Rounds x down to its nearest integer and floor(2.1) is 2
returns this integer. floor(-2.1) is -3
exp(x) Returns the exponential function of x (e^x). exp(1) is 2.71828
log(x) Returns the natural logarithm of x. log(2.71828) is 1.0
log(x, base) Returns the logarithm of x for the specified log10(10, 10) is 1
base.
sqrt(x) Returns the square root of x. sqrt(4.0) is 2
sin(x) Returns the sine of x. x represents an angle sin(3.14159 / 2) is 1
in radians. sin(3.14159) is 0
asin(x) Returns the angle in radians for the inverse asin(1.0) is 1.57
of sine. asin(0.5) is 0.523599
cos(x) Returns the cosine of x. x represents an cos(3.14159 / 2) is 0
angle in radians. cos(3.14159) is -1
acos(x) Returns the angle in radians for the inverse acos(1.0) is 0
of cosine. acos(0.5) is 1.0472
tan(x) Returns the tangent of x. x represents an tan(3.14159 / 4) is 1
angle in radians. tan(0.0) is 0
fmod(x, y) Returns the remainder of x/y as double. fmod(2.4, 1.3) is 1.1
degrees(x) Converts angle x from radians to degrees degrees(1.57) is 90
radians(x) Converts angle x from degrees to radians radians(90) is 1.57

12. Checkpoint
• 1. What is a variable?
• 2. Why do we have naming conventions?
• 3. What is the difference between a programming
expression and a statement?