Math Puzzle- Secret Santa

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Across
  1. 5. comes after a full stop.
  2. 7. out of 100.
  3. 8. 2D shape with no sides, or corners.
Down
  1. 1. Measure of outside of a shape.
  2. 2. needed for a maths problem (not numbers).
  3. 3. first n_______r, then a line, then d_______r.
  4. 4. alphabet in maths.
  5. 6. Space inside a shape.