Our new international survey across 33 countries shows just how wrong the world is about a range of key social realities. British people think the top 1% wealthiest households own 59% of their country’s wealth, when they actually “only” own 23%. Americans think that 33% of their population are immigrants, when in fact it is only 14%. Brazilians think the average age in their country is 56, when it is only 31. Russians think that 31% of their politicians are women, when it is only 14%. In Britain, people think that an extraordinary 43% of young adults aged 25-34 still live at home with their parents, rather than the actual 14%. In India, the online population think 60% of the whole country also has internet access, when in fact only 19% do. Why are people across the world so often so clueless about these realities? It is partly that we just struggle with basic maths and some of us clearly misunderstand the questions or interpret them differently. For example, most countries hugely overestimate how many people do not affiliate themselves with a religion: across the 33 countries, 37% do not, according to respondents, but the average is actually just 18%. This will be partly because we will be thinking of how many people practise their religion, rather than what they put on census forms. People also take mental shortcuts, where they grab for easily available