Maths

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Across
  1. 2. Odd (4)
  2. 5. How long did it take to build the wall of China?(9)
  3. 8. Early version of Sudoku (11)
  4. 10. Who invented 0? (5)
Down
  1. 1. Who was the first sovereign of china? (13)
  2. 3. How long is the wall of china? (9)
  3. 4. how many maths schools were in the 13th century? (2)
  4. 6. Even (6)
  5. 7. Leonardo of Pisa other name (9)
  6. 9. 4 is what to the Chinese? (3)