Which country has toughest maths?

But when it comes to having the hardest math, China and South Korea top the list.

What is the easiest math problem in the world?

If by ‘simplest’ you mean easiest to explain, then it’s arguably the so-called ‘Twin Prime Conjecture‘. Even schoolchildren can understand it, but proving it has so far defeated the world’s best mathematicians. Prime numbers are the building blocks from which every whole number can be made.