Your first Python program: input to output.

Preview editorial draft · September 2026

A variable is a name that refers to a value. A simple Python program can collect values, calculate a result and display an answer.

Read a name

name = input("What is your name? ")
print("Hello,", name)

input() returns text. The variable name holds that text, and print() displays the greeting.

Calculate an area

length = float(input("Length in metres: "))
width = float(input("Width in metres: "))
area = length * width
print("Area:", area, "square metres")

float() converts a valid numerical string into a number that can include a decimal part. Multiplication uses the * symbol.

Think about invalid input

This small example assumes the user enters valid, positive numbers. Text such as “five” will cause a conversion error. A production program needs input validation and a helpful way to retry.

Use meaningful names

Prefer total_score over x when the variable represents a total score. Python names are case-sensitive, so score and Score are different names.

Practice

1. Run the area example with length 5 and width 4. The result should be 20.
2. Change it to calculate perimeter using 2 * (length + width).
3. Predict the result before running it.