if n is 7 then no matter how many or few i take my opponent will take the rest on his turn
if n is 8 i take 1 leaving 7, no matter what amount my opponent takes i can take the rest thereby winning
if n = 9 i take 2 and the same outcome as the previous example
if n= 10 i take 3 leaving again 7 and forcing my opponent to leave a number equal to or less than 6 and equal to or more than 1