Beyond the answers - interesting background to this quiz

Why Roman numerals still show up on buildings and clocks

The quiz asks you to convert LXXX, which is simply 50 (L) plus three tens (XXX), giving 80. Roman numerals were the standard counting system across much of Europe for centuries before Arabic numerals gradually replaced them in everyday arithmetic. They never fully disappeared: you still see them on clock faces, in film credits, on monuments and in the names of popes and monarchs. The system is additive at heart, which is why reading a long numeral often means adding from left to right.

Two capitals that are often confused with their neighbours

Tunis and Rome both appear in this quiz, and both have neighbours that regularly get mixed up with them. Algiers is the capital of Algeria, not Tunisia, while Tripoli belongs to Libya. Rome, meanwhile, is easy to confuse with other major Italian cities such as Naples or Milan, though it is the country's capital and its largest city. Tunisia sits at the northern tip of Africa, and its capital, Tunis, lies close to the Mediterranean coast and to the ruins of ancient Carthage.

A lake that sits higher than most ski resorts

Lake Titicaca, on the border between Peru and Bolivia, is often described as the highest large lake in the world, sitting roughly 3,800 metres above sea level. By contrast, the Great Lakes of North America, including Ontario and Michigan, lie at low elevations and are far larger by surface area. Titicaca's altitude makes the surrounding air thin and the sunlight intense, and the lake has long been central to the cultures of the Andes, including the Uros people and their floating islands.

The planet with the most varied surface

Earth wins this one, and the reason is plate tectonics combined with water and weather. Our planet has mountain ranges, deep ocean trenches, deserts, ice sheets and volcanic islands, all shaped by moving crustal plates and erosion. Mars has the tallest volcano in the solar system and a vast canyon system, but its surface features are largely ancient and inactive. Venus is covered by thick clouds and mostly flat volcanic plains, which leaves Earth as the most geologically diverse of the three.