Maths puzzle

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Across
  1. 2. moving forward
  2. 5. sum of two terms
  3. 6. can be positive negative 0
  4. 8. has only one dimension
  5. 10. connected with lines
  6. 13. !
  7. 14. one after another
Down
  1. 1. different
  2. 2. number of ways
  3. 3. direction f line
  4. 4. one dimensional structure
  5. 7. closed plain with 3 sides
  6. 9. non equal
  7. 11. things that happen one after another
  8. 12. with no bends and curves