Luisa wants to buy a new laptop for work. She goes to the shop and asks: 'How much does this laptop cost?' The sales assistant says: 'It costs eight hundred euros. But we have a special offer this week — there is a twenty percent discount.' Luisa does the maths. Eight hundred minus twenty percent is six hundred and forty euros. 'That is good,' she says. 'Can I pay in instalments?' 'Yes,' says the assistant. 'The total is six hundred and forty euros, in four payments of one hundred and sixty.' Luisa is happy. She buys the laptop.

💡 Did you know? The most expensive item ever sold at auction was a Leonardo da Vinci painting called Salvator Mundi. It sold for over 450 million US dollars in 2017.