Lesson 1: Numbers and sums: what does Ben owe?

Module 2 · Lesson 1 · About 35 minutes · Needs: Module 1 (print, variables, reading an error)

The situation

Amira has a question for you this morning: "What does Ben owe if he is 9 days late?" Ben borrowed The War of the Worlds (loan L13) and has not brought it back. Today is Wednesday 14 October 2026.

In Module 2 dates are shelf days: the day's number counted from 1 September, so 14 October is day 44. Ben borrowed on day 21. A loan lasts 14 days, and the fee is 20 pence for each day late. Answering Amira takes three sums. This lesson teaches the numbers and operators that do them, and one trap with decimals that real systems have fallen into.

Each box is one number your code will work out; the green one is Amira's answer.