perplexus.info :: Numbers : Duplicate Digit Determination

Duplicate Digit Determination (Posted on 2006-12-03)

If 2^P and 5^P start with the same (non-zero) digit for positive integer P, what is that digit? Can you prove it must be so?

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Answer

Comment 6 of 6 |

The required common first digit of 2^P and 5^P is 3, since each of 2^5 and 5^5 starts with 3

Edited on December 30, 2022, 4:36 am

Posted by K Sengupta on 2008-11-08 00:53:38

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