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3 and 4-digit numbers (Posted on 2017-07-17) Difficulty: 2 of 5
Consider the number 4808
Notice: 4^2+8^2=80
i.e. the sum of the squares of this number's first and last digits equals the number obtained when the first and last digits are erased.

How many numbers with such feature exist below 10000?

Clearly, no leading zeroes.

  Submitted by Ady TZIDON    
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Solution: (Hide)
There are 83 numbers that qualify (see detailed answers by solvers).

Comments: ( You must be logged in to post comments.)
  Subject Author Date
re(4): Just counting (spoiler)Steve Herman2017-07-18 09:08:51
re(3): Just counting (spoiler)Charlie2017-07-17 21:59:59
Solutionre(3): Just counting (spoiler)Ady TZIDON2017-07-17 14:16:13
re(2): Just counting (spoiler)Steve Herman2017-07-17 13:59:08
re: Just counting (spoiler)Charlie2017-07-17 13:53:40
Just counting (spoiler)Steve Herman2017-07-17 13:08:18
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