Math CentralQuandaries & Queries


Question from Hangsun, a parent:

When 2 two digit numbers are added what is the greatest possible sum of the ones?

The units digit or the ones digit of an integer is the rightmost digit. For example the integer 564 has ones digit 4. I think this question is asking if you have 2 two digit numbers what is the largest value possible for th sum of the ones digits. Since the digits are 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 the largest the digits can be is 9 so the largest possible sum is 9 + 9 = 18.


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