Beyond the answers - interesting background to this quiz

A writer who knew the frozen North first-hand

Jack London, who wrote The Call of the Wild, did not simply imagine his setting. As a young man he joined the Klondike Gold Rush in Canada's Yukon, an experience that shaped much of his later fiction. The novel, published in 1903, follows a dog named Buck as he is taken from a comfortable California home and forced into the harsh life of a sled dog. Its portrait of survival and instinct made it one of the most widely read American books of its era.

The house that became an American icon

Grant Wood painted "American Gothic" in 1930, showing a farmer and a woman standing in front of a white house with a distinctive pointed window. The building was real: Wood spotted it in Eldon, Iowa, and used it as the backdrop for the figures. The models were his sister and his dentist, though Wood insisted they were not meant as portraits. The painting became one of the most recognisable - and most parodied - images in American art.

Why capitals are not always the biggest city

Washington, D.C. is the capital of the United States, yet New York is far larger, and Mexico City is both the capital and the biggest city in Mexico. This difference is common around the world. Some countries build a purpose-made capital to separate government from the commercial life of a major metropolis, while others simply place their seat of power in the largest urban centre. Both approaches have shaped how nations organise themselves.

Roman numerals and the numbers we use today

LXXV stands for 75: L is 50, and each X adds 10, with V for 5. Roman numerals served Europe for centuries, but they are awkward for calculation - try multiplying LXXV by IX without converting first. The Arabic numeral system, which reached Europe through medieval translations of works from the Islamic world, introduced the digit zero and a place-value structure. That made arithmetic far simpler and helped it gradually replace Roman figures in everyday use.