||Our goal is to study Pascal-Sierpinski gaskets, which are certain fractal sets deﬁned in terms of divisibility of entries in Pascal’s triangle. The principal tool is a “carry rule” for the addition of the base-q representation of coordinates of points in the unit square. In the case that q = p is prime, we connect the carry rule to the power of p appearing in the prime factorization of binomialcoeﬃcients. We use the carry rule to deﬁne a family of fractal subsets Bqr of the unit square, and we show that when q = p is prime, Bqr coincides with the Pascal-Sierpinski gasket corresponding to N = pr . We go on to describe Bqr as the limit of an iterated function system of “partial similarities”, and we determine its Hausdorﬀ dimension. We consider also the corresponding fractal sets in higher-dimensional Euclidean space.