puzzle time

123456789101112
Across
  1. 3. halfhour
  2. 6. smallestfourdigitnumber
  3. 7. karpekarconstant
  4. 9. one,three,six
  5. 10. smallestpolygon
  6. 11. one+two+one
  7. 12. halfcentury
Down
  1. 1. largestfourdigitnumber
  2. 2. one,two,three
  3. 4. acuteangle
  4. 5. acuteangle
  5. 8. answerofdivision