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🌱 Beginner

Python Numbers – int, float, complex and Math Operations

Numbers are at the core of almost every program. Python has three built-in number types: int (whole numbers), float (decimal numbers), and complex (numbers with imaginary parts). This lesson covers all three, along with arithmetic operators, the math module, rounding, and common number operations.

⏱️ 18 min read 🎯 Beginner 📅 Updated 2026

Integers (int)

Integers are whole numbers — positive, negative, or zero. Python integers have unlimited precision: they can be arbitrarily large with no overflow.

Python
x = 10
y = -5
z = 0
big = 10 ** 100  # Python handles huge numbers!

print(type(x))   # 
print(big)       # 1 followed by 100 zeros
▶ Output
10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

Floats (float)

Floats are decimal numbers. They use 64-bit IEEE 754 double-precision, which means they have ~15-17 significant digits but can have precision issues.

Python
pi = 3.14159
temp = -23.5
scientific = 1.5e-3   # 0.0015

print(type(pi))   # 
print(0.1 + 0.2)  # Floating point gotcha!
print(round(0.1 + 0.2, 2))  # Fix: use round()
▶ Output
0.30000000000000004 0.3
💡
Tip

Never use floats for financial calculations. Use the decimal module instead: from decimal import Decimal

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Arithmetic Operations

Python supports all standard arithmetic operations. Note: ** is power, // is floor division, % is modulo (remainder).

Python
a, b = 17, 5

print(a + b)   # 22  - addition
print(a - b)   # 12  - subtraction
print(a * b)   # 85  - multiplication
print(a / b)   # 3.4 - true division (always float)
print(a // b)  # 3   - floor division (rounds down)
print(a % b)   # 2   - modulo (remainder)
print(a ** b)  # 1419857 - power (17^5)
▶ Output
22 12 85 3.4 3 2 1419857

The math Module

Python's built-in math module provides advanced mathematical functions.

Python
import math

print(math.sqrt(16))    # 4.0 - square root
print(math.pi)          # 3.141592653589793
print(math.ceil(4.2))   # 5 - round up
print(math.floor(4.8))  # 4 - round down
print(math.log(100, 10))# 2.0 - log base 10
print(math.factorial(5))# 120
print(math.gcd(48, 18)) # 6 - greatest common divisor
▶ Output
4.0 3.141592653589793 5 4 2.0 120 6

Number Type Conversion

Convert between number types with int(), float(), and complex(). Note that int() truncates (does not round) floats.

Python
print(int(3.9))     # 3 - truncates, does NOT round
print(float(5))     # 5.0
print(int("42"))    # 42 - from string
print(float("3.14"))# 3.14

# Check if string is numeric before converting
value = "123"
if value.isdigit():
    print(int(value) * 2)  # 246
▶ Output
3 5.0 42 3.14 246
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