Suppose n ≥ 2 and A i ⊂ {0, 1, · · · , (n − 1)} for i = 1, · · · , l, let K i = a∈A i n −1 (K i + a) be self-similar sets contained in [0, 1]. Given m 1 , · · · , m l ∈ Z with i m i = 0, we let Sx = {(y 1 , · · · , y l ) : m 1 y 1 + · · · + m l y l = x with y i ∈ K i ∀i} .In this paper, we analyze the Hausdorff dimension and Hausdorff measure of the following set Ur = {x : Card(Sx) = r}, where Card(Sx) denotes the cardinality of Sx, and r ∈ N + . We prove under the so-called covering condition that the Hausdorff dimension of U 1 can be calculated in terms of some matrix. Moreover, if r ≥ 2, we also give some sufficient conditions such that the Hausdorff dimension of Ur takes only finite values, and these values can be calculated explicitly. Furthermore, we come up with some sufficient conditions such that the dimensional Hausdorff measure of Ur is infinity. Various examples are provided. Our results can be viewed as the exceptional results for the classical slicing problem in geometric measure theory.2000 Mathematics Subject Classification. Primary 28A80.