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225 as a factor (Posted on 2022-04-12) Difficulty: 3 of 5
Please specify how many positive integers display the following features:
a. The number is below 10^12.
b. It is a multiple of 225.
c. Its decimal representation involves only two distinct digits.

Provide a justification of your result..

See The Solution Submitted by Ady TZIDON    
Rating: 5.0000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re(2): Analytic solution | Comment 4 of 7 |
(In reply to re: Analytic solution by Charlie)

Thank you, Charlie.


I ran mine for power = 9 and 10; extrapolating the time came to an estimate of 50 minutes, and "about an hour" is what I think it took when I ran it at 12.

I haven't used Matlab, but I would have thought it would be faster than Python (laptop with 2.6 GHz CPU)

9 272
['25', '09', '03', '57', '06']
2.859375 seconds

10 493
['25', '09', '03', '57', '06', '05']
31.71875 seconds

  Posted by Larry on 2022-04-12 13:12:21
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