The Mo You Know with Greek and Roman Numerals

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Across
  1. 1. A _agon has 7 sides
  2. 3. Halloween is in ___ber?
  3. 5. Duet includes _ people?
  4. 6. Decibels is on a scale of 1 to _?
  5. 8. A septet has_ member?
  6. 9. This means both a- - -?
  7. 12. To annihilate something is to make it _?
  8. 14. This number is at the top of Big Ben's Clock Face X_ _.
  9. 15. This means 100 and a half ____ centennial
  10. 17. Steve Irwin died this year (10 years from 2016)
  11. 18. The upcoming Superbowl in 2022 is Superbowl L- -
Down
  1. 2. A prototype is a _ of its kind?
  2. 4. 2011 was a what- - - -de ago?
  3. 7. This is 55 in roman numerals.
  4. 8. Solitary is a game played _?
  5. 10. This year in Roman numerals
  6. 11. A uniform makes a team _?
  7. 13. Earth is cut into _ hemispheres?
  8. 16. A semicircle is what of a circle?