perplexus.info :: Just Math : Units Digit Determination

Units Digit Determination (Posted on 2015-01-07)

N is a 9-digit duodecimal (base 12) palindrome such that:

The first two digits of N are not consecutive, and:
The sixth and seventh digits of N are not consecutive

What is the units digit of the sum of all possible values of N?

How about N being a 9-digit hexadecimal (base 16) palindrome instead?

*** N is of course positive and does not contain any leading zero.

Submitted by K Sengupta

Rating: 4.0000 (2 votes)

Solution: (Hide)

(i) The required unit digit sum is 0 in base 12.
(ii) The required unit digit sum is 0 in base 16.
For an explanation, refer to the solution submitted by Steve Herman in this location, which has been corroborated by Charlie in this location.

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
corrected computer summation	Charlie	2015-01-08 07:59:42
Adding up those 9-digit numbers	Charlie	2015-01-07 15:12:43
Simple analysis (spoiler?)	Steve Herman	2015-01-07 15:01:34

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