Numbers

Numbers

Python has three numeric types: int, float, and complex.

int

Whole numbers, positive or negative, with no decimal point:

x = 1
y = 35656222554887711
z = -3255522

Python ints can be as big as you want; no overflow.

float

Numbers with a decimal point or in scientific notation with an e:

x = 1.10
y = 1.0
z = -35.59
big = 35e3      # 35000.0
small = 12E4    # 120000.0

complex

Numbers with a real and imaginary part, written with a j:

x = 3 + 5j
y = 5j
z = -5j

Check the type

print(type(10))     # <class 'int'>
print(type(10.0))   # <class 'float'>
print(type(3 + 5j)) # <class 'complex'>

Convert between types

Use int(), float(), and complex():

x = 1    # int
y = 2.8  # float
z = 1j   # complex

a = float(x)    # 1.0
b = int(y)      # 2
c = complex(x)  # (1+0j)

Note: you can't convert a complex number to int or float directly.

Random numbers

Python has no built-in random number function, but the random module has plenty:

import random
print(random.randrange(1, 10))

TL;DR

• Three numeric types: int, float, complex.
• ints are unlimited size; floats use a decimal or e notation.
• Complex numbers use a j for the imaginary part.
• int(), float(), complex() convert between them.
• random.randrange from the random module gives random ints.