Cube Root of 686

Cube Root Calculator
Cube root of

What is the cube root of 686?

Answer

∛686 =
7∛2 ≈ 8.8194

Real cube root: the only number whose cube is 686.

≈ — rounded to 4 decimal places. 686 is not the cube of a rational number, so ∛686 is irrational: its decimal expansion never ends and never repeats.

Prime factors
686 = 2 × (7 × 7 × 7) = 2 × 7³
Take out of the root
∛686 = ∛(7³ × 2) = 7∛2
Between cubes
8³ = 512 < 686 < 729 = 9³, so 8 < ∛686 < 9 and ∛686 ≈ 8.8194

Related Calculations

See Also

Cube roots of nearby values

FAQ

What is the cube root of 686?

∛686 = 7∛2 ≈ 8.8194

How to simplify ∛686?

Factor 686 into primes: 686 = 2 × 7 × 7 × 7. Each triple of equal factors is a cube and comes out of the root as one factor; the rest stays under it: ∛686 = ∛(7³ × 2) = 7∛2.

Is ∛686 a rational number?

No: 686 is not the cube of a rational number, and the cube root of a fraction p/q in lowest terms is rational only when p and q are both cubes. So ∛686 is irrational; its decimal never ends and never repeats: ∛686 ≈ 8.8194.