Easy crossword

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Across
  1. 3. what we will do to subtract 1000 to get 799?
  2. 5. 5550 add 50?
  3. 6. multiply 24 by 39?
  4. 8. divide 54 by 5?
Down
  1. 1. what will we add at 500 to get 900?
  2. 2. what will we add in 800 to get 2000?
  3. 3. 400 subtract 200?
  4. 4. what we will do to subtract 500 to get 311?
  5. 7. add 5550 by 1000?
  6. 8. if I have 900 rings and my friend has 400 rings how many rings are in total?