Integers

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Across
  1. 4. ____________ property of addition states that a+(b+c)=(a+b)+c for integers a,b and c.
  2. 7. All natural numbers,zero and negatives of natural numbers.
  3. 8. _________ property of multiplication states that a*b=b*a.
  4. 9. Product of a non-zero integer and zero.
Down
  1. 1. Sum of two positive integers-
  2. 2. 1 is the multiplicative _____________ for integers.
  3. 3. Operation under which integers are not closed.
  4. 5. Sum of two negative integers-
  5. 6. -a is the additive ___________ of the integer a.