Integer Puzzle

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Across
  1. 2. When two numbers are added, the sum is the same no matter the order of the addends
  2. 4. Putting two or more numbers together
  3. 6. Taking away a certain amount of a number
  4. 7. A number
  5. 9. A number above zero
  6. 13. Subtracting the same number from both sides of an inequality does not affect the inequality
  7. 16. A number below zero
  8. 17. Adding the same number to both sides of an inequality does not affect the inequality
  9. 19. A way of multiplication with a number outside of a problem with parentheses in it
Down
  1. 1. Adding the same number to both sides of an inequality does not affect the inequality
  2. 3. The sum of every number and zero is the original number
  3. 5. When three or more numbers are added, the sum is the same ni matter the order addends
  4. 8. The product of any number multiplied by 1 is that number
  5. 10. The quotient of any number divided by 1 is that number
  6. 11. The difference of any number subtracted by zero is that number
  7. 12. Repeated addition
  8. 14. Dividing both sides of an equation by a non-zero number doesn't affect the equation
  9. 15. To put something together
  10. 18. This word uses a fraction bar in the process