Calculus

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Across
  1. 2. there's multiple of it
  2. 4. What we should have learned by now
  3. 7. We do it often
  4. 9. counterpart to what there's multiple of
  5. 10. The secret___
  6. 12. etisoppo s'tI
  7. 14. sounds like tetris
  8. 15. It's a *component of what we do
Down
  1. 1. It's *integral to what we do often
  2. 3. It's simple, but still a big plus
  3. 5. almost equal
  4. 6. It's math related
  5. 8. It quantifies what we do often
  6. 11. It's what we do often, but *minus a few steps
  7. 13. Not a formula, but an___