A 7-digit base ten positive integer of the form ABCDEFG is called a modified hill number if the digits B, D and F satisfies: B = A + C (mod 10) , D = C + E (mod 10) and F= E + G (mod 10) (Each of the capital letters in bold denotes a digit from 0 to 9, whether same or different.)

Determine the probability that x is a modified hill number, given that x is a base ten positive integer chosen at random between 1000000 and 9999999 inclusively.

(In reply to re: answer by Charlie)

(2+9) mod 10 = 1
 2+9 (mod 10) = 11

Note: 9 (mod 10) is still 9 
Of course, why even include (mod 10) if it were to be referencing a single digit? It would be extraneous.  Yet, it is incorrect format for the other interpretation.

Edited on March 11, 2011, 6:08 pm

Posted by Dej Mar on 2011-03-11 17:53:06