random number guessage problems

here is the problem. I am making a (single digit) random number Guesser, it tries to guess the next number based on the preveous numbers and how many numbers have been entered since the start of the session. random numbers are entered one after the other, like 93659163. (when training) I store all the numbers in a format like this: typedef struct { char thenumber; //number entered int freq; //times this pattern has happened before int history; //count of guesses in the session before this arose char lastno; // the number before this char lastno2; // the number before that above char lastno3; // the number before that above } numentry; I need to devise a scoring system for the most likly next number based on a database of previous examples. at first i thought points = (for each matching param +=5) (+frequency), but a numentry with a high frequency will win even if it is totaly unrelated to the previous numbers. DO you have any suggestions?