Python: Modules

A Python file with functions and constants is called a module. You can connect it to your program using the import keyword and use ready-made code instead of writing it yourself.

Python comes with a standard library — a set of modules included with the language. One of the most commonly used is math, which provides mathematical functions and constants.

Importing a Module

The import command at the top of a file makes the module's contents available:

import math

print(math.floor(3.7))  # => 3
print(math.ceil(3.2))   # => 4

After importing, you access functions through the module name and a dot. math.ceil(3.2) calls the ceil function from the math module.

Functions in the math Module

floor rounds a number down to the nearest integer, ceil rounds it up:

import math

print(math.floor(7.9))  # => 7
print(math.ceil(7.1))   # => 8
print(math.ceil(7.0))   # => 7

The difference matters when the number is not whole. floor(7.9) gives 7, not 8, because 7 is the nearest integer below.

Importing Specific Names

When you only need part of a module, you can import specific names:

from math import ceil, floor

print(ceil(3.2))   # => 4
print(floor(3.7))  # => 3

This lets you use ceil and floor directly, without the math. prefix. The result is the same as using import math.

Using a Module Inside a Function

An imported module is available throughout the file, including inside function bodies:

import math

def trips_needed(items: int, capacity: int) -> int:
    return math.ceil(items / capacity)

print(trips_needed(10, 3))  # => 4

The function trips_needed uses math.ceil. The import math line at the top of the file makes this possible.

Implement the function amount_per_person(). It takes the restaurant bill total, the number of people, and the tip percentage, and returns the amount each person pays. The result is rounded up — nobody should underpay.

Use the math.ceil() function from the math module for rounding.

# Bill 300, 4 people, 20% tip — total 360, each pays 90
print(amount_per_person(300, 4, 20))  # => 90

# Bill 350, 3 people, 10% tip — total 385, each pays 129
print(amount_per_person(350, 3, 10))  # => 129

Hint

• First calculate the total with tip, then divide by the number of people and round up
• Don't forget to import the math module at the top of the file