number prefix crossword puzzle

123456789101112131415161718
Across
  1. 3. shape with four sides
  2. 5. one wheel bike
  3. 7. nine
  4. 8. many sides to a shape
  5. 9. sea creature with eight legs
  6. 10. two joining into one
  7. 14. two hundred years
  8. 15. one hundred years
  9. 16. five point star that is intersected in center
  10. 18. six
Down
  1. 1. one of four parts
  2. 2. many
  3. 4. part of ten in places
  4. 6. one control over many things
  5. 11. having three angles
  6. 12. ten
  7. 13. prefix for one
  8. 17. one voice that is the same