x = {2, 12, 8, 5, 18, 25};
n = N Items( x );
For( i = 1, i <= n, i++,
If( x[i] <= 10,
x[i] = x[i] ^ 2
)
);
Show( x );
x = {4, 12, 64, 25, 18, 25};
You can use Loc() to locate the items in the new list that are equal to 25:
Loc( x, 25 );
[4, 6] // The fourth and sixth items in the list are equal to 25.