Numbers and Ancient Civilizations

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Across
  1. 7. used letters to represent numbers
  2. 8. developed the Ionic number system
  3. 10. wrote their numbers on clay tablets
  4. 12. copied their number system from the Greeks
  5. 13. wrote numbers vertically from top to bottom
Down
  1. 1. used knotted rope to record numbers
  2. 2. built the pyramids
  3. 3. used wedges to represent numbers
  4. 4. marks notched into bone
  5. 5. used pictures to represent numbers
  6. 6. used a shell to represent zero
  7. 9. represented five to the Mayans
  8. 11. knotted ropes