The math toolbox

Built-in tools need no import: round(x, 2) rounds x to 2 decimal places (an exact half goes to the even neighbour, so round(2.5) is 2 and round(3.5) is 4), abs(-4) gives the distance from zero (4), max(3, 9) gives the largest value (9), and min(3, 9) gives the smallest (3).

More tools live in the math module. Import it once at the top:

import math
math.pi          # 3.14159...
math.sqrt(16)    # 4.0
math.ceil(4.1)   # 5  (round up)
math.floor(4.9)  # 4  (round down)

See it run

import math
x = 7.6
print(round(x), math.floor(x), math.ceil(x))
print(math.sqrt(49))

import math unlocks extra tools. Watch how three ways of rounding treat the same number.

Practice the math toolbox

Exercise 1

area: the area of a circle with radius = 3 (π × r²), rounded to 2 decimals (28.27).
boxes: you need to ship 23 cups, 5 per box. How many boxes? Use math.ceil (5).

Exercise 2

TV sizes are measured corner to corner. A screen is width = 16 and height = 9 (inches). Make diagonal = √(width² + height²) using math.sqrt, rounded to 1 decimal (18.4).

Exercise 3

You are painting a wall 4.2 m wide and 2.6 m tall with 2 coats. One tin covers 10 m².

area_needed = width × height × coats, rounded to 2 decimals (21.84)
tins = how many tins to buy (you can't buy part of a tin): 3
leftover = m² of paint left over, rounded to 2 decimals (8.16)

Free lesson: use the editor to practice it.

Practice

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Memory · names → values

Variables appear here as Python creates them.

Output & plots