after the second clue your possibilities are 19 39 59 79 90 91 92 93 94 95 96 97 98 99, i would have entered a number in the middle like 92 then found out its higher, having 2 guesses left and possibilities 93 94 95 96 97 98 99 pick the middle again being 96, if high or lower i would only have 3 numbers to pick for the last chance, i find this sort of method works much better and in this case i would have had better than 33% chance to get it right in the end