- How old is the abacus?
- Who is the father of Abacus?
- What is the full name of Abacus?
- What replaced the abacus?
- What is the cost of Abacus?
- Is Abacus still used today?
- Who invented zero?
- Who invented maths?
- When and who invented the abacus?
- Which type of Abacus is best?
- How do you spell abacus?
- Who invented Abacus in India?
- What is Chinese abacus called?
How old is the abacus?