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Only prime digits allowed (Posted on 2019-01-31)

List all the integers containing only prime-digits such that their squares also contain prime-digits only.

Hint: The highest qualifying number is below 77777.

Source: Claudio Meller's site.

See The Solution Submitted by Ady TZIDON

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Puzzle Solution

Comment 2 of 2 |

The required positive integers are 5, 235 and 72335, since:

5^2 = 25

235^2 = 55225

72335^2 = 5232352225

Posted by K Sengupta on 2022-06-08 00:04:23

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