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Rani needs the largest whole number whose cube is still less than 500. Which number is it?

Class 8Cubes and Cube RootsCubes and Roots
  • A6
  • B8
  • C22
  • D7

Step-by-Step Solution

is under 500 while goes over, so 7 is the largest. Answering 22 uses the square root of 500 (about 22.4) instead of the cube root, and 6 stops one step early at 216.
Answer: D) 7

Key idea: Squares vs cubes — what's different

Both are repeated multiplication, but with key differences:

- A square is non-negative: .
- A cube **keeps the sign**: . (Three negatives stay odd → still negative.)
- Squares grow more slowly than cubes: vs For square roots, only positive results (by convention). For cube roots, the sign matches the input: ∛.

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