Basics

Numbers

Python numbers include integers, floats, and complex values.

Python has int for whole numbers and float for approximate real-valued arithmetic. True division with / returns a float, even when both inputs are integers.

Source

count = 10
ratio = 0.25

print(count + 5)
print(count / 4)
print(ratio * 2)

Output

15
2.5
0.5

Floor division and modulo are useful when you need quotient and remainder behavior. Powers use **, not ^.

Source

print(count // 4)
print(count % 4)
print(2 ** 5)

Output

2
2
32

Complex numbers are built in. The literal suffix j marks the imaginary part.

Source

z = 2 + 3j
print(z.real, z.imag)

Output

2.0 3.0

Floating-point values are approximate, so == between expected and computed floats is rarely the right test. Compare with math.isclose (or work in decimal.Decimal) when the question is "are these the same number to within tolerance".

Source

import math

print(0.1 + 0.2)
print(0.1 + 0.2 == 0.3)
print(math.isclose(0.1 + 0.2, 0.3))
print(round(3.14159, 2))

Output

0.30000000000000004
False
True
3.14

Notes

Python's int has arbitrary precision; it grows as large as memory allows.
Python's float is approximate double-precision floating point.
Use / for true division and // for floor division.
Use math.isclose instead of == for floating-point comparison; reach for decimal.Decimal when exact decimal precision is the domain requirement.

Run the complete example

Expected output

15
2.5
2
2
32
2.0 3.0
0.30000000000000004
False
True
3.14

Execution time appears here after you run the example.

Numbers

See also

Run the complete example

Example code

Expected output