Cube roots, step by step
A cube root asks which number, multiplied by itself three times, gives this one.
The question
∛1331
∛1331=▢
10³=1000— under
20³=8000— over
∛1331is between10 and 20
∛1331=11
11 × 11 × 11=1331
∛1331=11
- ∛ asks a question: which number, used three times as a factor, gives 1331? It is not an instruction to divide 1331 by 3 — that is the mistake this symbol collects.
- Bracket it first. 10³ = 1000, which is under 1331, and 20³ = 8000, which is over. So the answer is between 10 and 20.
- Now the last digit. 1331 ends in 1, and the only digit whose cube ends in 1 is 1. Between 10 and 20 that leaves 11.
- Check it: 11 × 11 × 11 = 1331. So ∛1331 = 11.
How it works.
- 01
∛ asks a question: which number, used three times as a factor, gives 1331? It is not an instruction to divide 1331 by 3 — that is the mistake this symbol collects.
- 02
Bracket it first. 10³ = 1000, which is under 1331, and 20³ = 8000, which is over. So the answer is between 10 and 20.
- 03
Now the last digit. 1331 ends in 1, and the only digit whose cube ends in 1 is 1. Between 10 and 20 that leaves 11.
- 04
Check it: 11 × 11 × 11 = 1331. So ∛1331 = 11.