23.

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Across
  1. 1. 1962 Presley film (do the math)
  2. 4. :, in math
  3. 5. Abbr. in a math textbook
  4. 6. A in math
  5. 8. (0,0), in math: abbr.
Down
  1. 2. 1970 war film (do the math)
  2. 3. -- diagram (math graph)
  3. 7. 18th-century Swiss math great