Hard Puzzle

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Across
  1. 2. 492400-66
  2. 4. five thousand six hundred seventy eighty
  3. 9. 324000+668
  4. 10. 400+259
  5. 12. one hundred nine thousand nine hundred ninety nine
  6. 17. eighty six thousand nine hundred ten
  7. 18. 2000+600
  8. 20. round to 10000
Down
  1. 1. you get 720 when you round to tens place
  2. 3. 29700-25
  3. 4. 50000+69
  4. 5. 80000+5000+600+60+6
  5. 6. one less than 400
  6. 7. 300000+20000
  7. 8. 2000+659
  8. 11. you get 5680 when you round to tens place
  9. 13. 900000+50000+6000+700+80+1
  10. 14. 9600-79
  11. 15. 200+98
  12. 16. 100+5
  13. 19. 40+60