8th Grade Math Problems With Answers Worksheets 8th Grade Math Problems With Answers - Onlinemath4all, = ∛ 256 = ∛ (2 ⋅2⋅2⋅2⋅2⋅2⋅2⋅2) When we group the prime factors inside the cube root as triples, we left over with 2 ⋅ 2.That is 4. Hence 4 is the smallest number required to divide 256 so that the quotient is a perfect cube.