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17 votes
17 votes
Find the unique two-digit number such that the square of the sum of digits equals the number obtained

by reversing its digits.

User Bittersour
by
2.6k points

1 Answer

24 votes
24 votes

Let the number be ab, where a and b are digits. This number is equal to 10a+b.

This means we need (a+b)² = 10b+a.

After some trial and error, we get a=1 and b=8, and thus the number is 18.

User Roger Allen
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3.0k points