Arithmetic operations are used to perform mathematical calculations on numeric values.

Python provides several arithmetic operators that can be used with integers, floating-point numbers, and complex numbers.

The most commonly used arithmetic operators are:

Operator	Operation
+	Addition
-	Subtraction
*	Multiplication
/	Division
//	Floor Division
%	Modulus
**	Exponentiation

Some of these operators will be discussed in greater detail later in this chapter.

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Example 1: Addition #

main.py

a = 15
b = 10

print(a + b)

Output #

25

Explanation #

• The + operator adds two numbers.
• The result is the sum of the operands.

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Example 2: Subtraction #

main.py

a = 25
b = 8

print(a - b)

Output #

17

Explanation #

• The - operator subtracts the second operand from the first.
• The result is the difference between the two numbers.

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Example 3: Multiplication #

main.py

length = 8
width = 5

area = length * width

print(area)

Output #

40

Explanation #

• The * operator multiplies two numbers.
• Here, it calculates the area of a rectangle.

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Example 4: Division #

main.py

a = 20
b = 4

print(a / b)

Output #

5.0

Explanation #

• The / operator performs floating-point division.
• Even when both operands are integers, the result is a float.

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Example 5: Mixed Arithmetic #

main.py

a = 15
b = 2.5

print(a + b)
print(a * b)

Output #

17.5
37.5

Explanation #

• Python allows arithmetic between integers and floating-point numbers.
• The integer is automatically converted to a float.
• The result is a floating-point number.

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Example 6: Arithmetic Expressions #

main.py

result = 10 + 5 * 2

print(result)

Output #

20

Explanation #

• Python follows operator precedence.
• Multiplication is performed before addition.
• Therefore:
  • 5 * 2 = 10
  • 10 + 10 = 20

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Example 7: Using Parentheses #

main.py

result = (10 + 5) * 2

print(result)

Output #

30

Explanation #

• Parentheses have the highest precedence.
• The addition is performed first.
• Then the multiplication is performed.

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Example 8: Arithmetic with Variables #

main.py

price = 250
quantity = 4

total = price * quantity

print(total)

Output #

1000

Explanation #

• Arithmetic operators work with variables as well as literals.
• Python substitutes the values stored in the variables before performing the calculation.

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Example 9: Arithmetic with Complex Numbers #

main.py

a = 3 + 2j
b = 1 + 4j

print(a + b)
print(a - b)

Output #

(4+6j)
(2-2j)

Explanation #

• Arithmetic operators also work with complex numbers.
• Python automatically performs the calculations on both the real and imaginary parts.

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Example 10: Multiple Operations #

main.py

a = 12
b = 4
c = 3

result = a + b * c - 6

print(result)

Output #

18

Explanation #

• Multiplication is performed first.
• The expression becomes:
  • 12 + (4 × 3) - 6
  • 12 + 12 - 6
  • 18

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Common Mistakes #

1. Assuming Division Returns an Integer #

Incorrect

print(20 / 5)

Incorrect Expectation #

4

Actual Output #

4.0

Reason

The / operator always returns a floating-point result.

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2. Ignoring Operator Precedence #

Incorrect

result = 10 + 5 * 2

Incorrect Expectation

30

Actual Result

20

Reason

Multiplication has higher precedence than addition.

Correct

result = (10 + 5) * 2

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3. Mixing Strings and Numbers #

Incorrect

print("10" + 5)

Output #

TypeError: can only concatenate str (not "int") to str

Reason

Arithmetic operators require compatible numeric data types.

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4. Dividing by Zero #

Incorrect

print(10 / 0)

Output #

ZeroDivisionError: division by zero

Reason

Division by zero is not allowed in Python.

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Best Practices #

• Use descriptive variable names in arithmetic expressions.
• Use parentheses to improve readability and avoid confusion.
• Remember that / always returns a floating-point value.
• Keep arithmetic expressions simple whenever possible.
• Convert user input to numeric types before performing calculations.

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Key Points to Remember #

• Arithmetic operators perform mathematical calculations.
• Python supports addition, subtraction, multiplication, division, floor division, modulus, and exponentiation.
• Arithmetic operators work with integers, floats, and complex numbers.
• Python follows operator precedence when evaluating expressions.
• Parentheses can be used to control the order of evaluation.
• The / operator always produces a floating-point result.
• Division by zero raises a ZeroDivisionError.