What number is associated with 'Lucky Number' in Italy?

What is the currency of Japan, related to Decimal System?

The 'metric system' became mandatory in which country first?

In which country was zero first used as a number?

Which country uses a comma (,) as the decimal separator?

What number is considered unlucky in China and some other East Asian countries, because it sounds like the word for 'death'?

Which country is known for popularizing Sudoku puzzles, involving number placement?

What is considered a 'Baker's Dozen' in many countries?

The abacus, an early calculating tool, originated in which country?

Which country uses the numbering system that is a base-20 number system?