(In reply to
re(2): solution by Ady TZIDON)
The way to edit one's comments is to select that comment, and below the comment's text will be a place where it says "This is your comment". Near that is a link that says "Edit comment". But this feature is generally looked upon as to be used only to correct typos, so a followup note is good as a general practice anyway (as I did in correcting my leaving out of the digit 3 in my analysis).
Regarding your correction to
"Remark(NOT NEEDED TO SOLVE THE PUZZLEW): the last digit of Nth power of any number is equal to the last digit of Kth power of said number iff(=if and only if) M mod 5= N mod 5 i.e. consider the 4th power instead of the 99th."
First I assume you mean K rather than M as M has not been introduced. And your correction indicates mod 4 rather than mod 5. So it would read
the last digit of Nth power of any number is equal to the last digit of Kth power of said number iff(=if and only if) K mod 4 = N mod 4 i.e. consider the 3rd power instead of the 99th.
Actually the word should be "if" rather than "iff", as K = N mod 4 (which is another way of saying K mod 4 = N mod 4) is sufficient for the last digits to be the same, but not always necessary. For example, 4^3 ends in 4 as does 4^5 even though 3 and 5 have different congruences mod 4. The "iff" holds in both directions only for numbers ending in 2, 3, 7 and 8; the other digits have cycles of length 1 or 2.

Posted by Charlie
on 20040123 10:38:36 