3 Arithmetic and Logical Operations and Expressions

Different data types can be operated on in many different ways. For this purpose, Python offers operators – symbols or keywords that tell Python what kind of operation to perform. For instance, most standard mathematical operation symbols can be used in Python for numerical data types. A code snipped that produces a value, from for example using operators, are referred to as Expressions.

3.1. Arithmetic Operators

Here is an overview of most of the basic arithmetic operations and their corresponding symbol. They are applied to numerical data and outputs a numerical value.

Operator	Description	Example	Result
+	Addition	3 + 2	5
-	Subtraction	3 - 2	1
*	Multiplication	3 * 2	6
/	Division (float)	3 / 2	1.5
//	Floor Division	3 // 2	1
%	Modulus (remainder)	3 % 2	1
**	Exponentiation	3 ** 2	9

a = 10
b = 3

sum_result = a + b # Output: 13
division_result = a / b # Output: 3.3333...
mod_result = a % b # Output: 1
square_result = a ** 2 # Output: 100

print("Sum of a and b:", sum_result)
print("Division of a and b: ", division_result)
print("Remainder of a and b:", mod_result)
print("Square of a:", square_result)

Sum of a and b: 13
Division of a and b:  3.3333333333333335
Remainder of a and b: 1
Square of a: 100

Important Note About Division

In Python, division using / always produces a float, even if the result looks like a whole number and integers were used for the division.

For example:

print(4 / 2) # Output: 2.0

You can combine multiple operators in a single expression. Python follows the standard order of operations rules (also known as BIDMAS or PEMDAS):

1. Parentheses.

2. Exponents.

3. Multiplication / Division.

4. Addition / Subtraction.

result = 3 + 5 * 2 # Output: 13
# Multiplication done first => 3 + 10 = 13
print(result)

parenthesised_result = (3 + 5) * 2 # Output: 16
# Parentheses first => 8 * 2 = 16
print(parenthesised_result)

13
16

3.2. Comparison Operators

These operators are used to compare two values (mainly numerical values - but could be other data types as well); the result is always a Boolean value (True or False).

Operator	Description	Example	Result
==	Equal to	3 == 2	False
!=	Not equal to	3 != 2	True
>	Greater than	3 > 2	True
<	Less than	3 < 2	False
>=	Greater or equal	3 >= 3	True
<=	Less or equal	3 <= 2	False

3.3. Logical Operators

Logical operators are used to operate on Boolean values and also return a Boolean.

Operator	Description	Example	Result
and	True if both conditions are True	(3 > 2) and (2 > 1)	True
or	True if at least one condition is True	(3 > 2) or (2 == 1)	True
not	Inverts the Boolean value (True becomes False)	not (3 > 2)	False

print(2 != 3) # Output: True
print((3 > 2) and (4 > 5)) # Output: False
print((2 < 5) or (10 < 3)) # Output: True
print(not (1 == 1)) # Output: False

True
False
True
False

3.4. Quick Practice

Try to guess the results of the following expressions. Feel free to write some code to double check your assumptions and play around with it:

• 5 + 2 * 3

• (5 + 2) * 3

• 10 // 3

• 10 % 3

• (5 > 3) and (2 < 1)

• 4 == 4

• not (4 == 4)

# Put your code here

💡 Solutions

print(5 + 2 * 3) # Output: 11
print((5 + 2) * 3) # Output: 21
print(10 // 3) # Output: 3
print(10 % 3) # Output: 1
print((5 > 3) and (2 < 1)) # Output: False
print(4 == 4) # Output: True
print(not (4 == 4)) # Output: False