Numbers / Integers

Numbers are the foundation of every programming language. In this module, we will learn how to use numbers in Python.

Python has three main numeric types:

• int for whole numbers (e.g. 2, -5)

• float for decimal numbers (e.g. 3.14, -0.5)

• complex for complex numbers (e.g. 2+3j)

bool is a subtype of int where False behaves like 0 and True behaves like 1.

Integers (int)

Integers are whole numbers of unlimited length.

positive_int = 2
negative_int = -2
zero = 0

Booleans (bool)

Booleans represent truth values: True and False.

is_raining = True
is_cloudy = False

Floats (float)

Floats are numbers with decimals.

float_number = 7.0
float_number_via_function = float(7)
float_negative = -35.59

Complex Numbers (complex)

Complex numbers have a real and imaginary part.

z = 2 + 3j
print(z.real)  # 2.0
print(z.imag)  # 3.0

Common Operations

a = 10
b = 3

print(a + b)  # 13
print(a - b)  # 7
print(a * b)  # 30
print(a / b)  # 3.333...

Useful Built-ins

print(type(5))        # <class 'int'>
print(isinstance(5, int))  # True
print(round(3.14159, 2))   # 3.14

Common Pitfalls

• 0.1 + 0.2 is not exactly 0.3 because of floating-point precision.

• Dividing two integers with / always returns a float.

References

Python Documentation

W3Schools

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