during input scanning ..when we found the string which can directly reduced to production variable...such part is called as handle...
now look at you string n+n*n;...
now when we read n then there is possible reduction from n to E...so first handle is 'n'..
now we have replace it with E...so we get E+n*n...now we continue scan and we can see that E+n is another one that can be reduce to E...so our next handle is E+n......so replace E+n with E only ..
now we have E*n....this is also one more handle as it can be directly reduct to E....
SO ALL HANDLES WE GET IN SEQUENCE ARE
n , E+n , E*n