For this case we have the following property of the sum:
Identity property of the sum: Adding 0 to any number results in the same number.
Therefore, Applying the property for this case we have:
17,985 + 0 = 17,985
We note that the result of the sum is the same number with which June started the sum.
Answer:
June used the following property of the sum:
Identity property of the sum.