math puzzle

12345678
Across
  1. 2. multiply 60x60
  2. 3. 50+50
  3. 4. 1000+4560
  4. 7. subtract 700 from 450
  5. 8. predecessor of largest 5 digit number
Down
  1. 1. successor of smallest four digit number
  2. 2. half of 7540
  3. 3. sum of 9104 and 1324
  4. 5. sum of 6788 and 1232
  5. 6. largest 3 digit number