Week 15 puzzle

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Across
  1. 3. not in first or third place
  2. 4. to be "out and _____"
  3. 5. math with variables
  4. 7. once more
  5. 10. a set of twelve
  6. 12. to size up against one another
  7. 13. an area
  8. 15. "how could that ____"
  9. 16. divided into four parts
  10. 17. invisible line about the earth
Down
  1. 1. one plus three zeros
  2. 2. volume in the library
  3. 5. as a dog, cat or tiger
  4. 6. to put a hole into
  5. 8. to bring a companion
  6. 9. not the same
  7. 11. an academic explanation
  8. 14. not the first choice, but the