Half of the square root of a number is 1. The number is
, 2012
Pick one
Solution
To make the difference as large as possible, we make one number as large as possible and the other number as small as possible.
The tens digit of a number contributes more to its value than its units digit.
Thus, we construct the largest possible number by choosing 8 (the largest digit) to be its tens digit, and by choosing 6 (the second largest digit) to be the ones digit.
Similarly, we construct the smallest possible number by choosing 2 (the smallest digit) to be its tens digit, and 4 (the second smallest digit) to be its ones digit.
The largest possible difference is .
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