Theory:

Do you ever heard the word cube before?

Yes, we know that a cube is a $$3$$-dimensional figure; we already studied it in earlier classes.

Recall:
A cube is a solid figure, which has all sides of equal length.

If you multiply a number by itself and then by itself again (thrice), the product is a cube number. It is also called as a perfect cube. That is, if $$a$$ is a number, its cube is represented by $$a^3$$.
Example:
Let us find the cube number of $$3$$.

Here, $$a = 3$$.

$$a^3 = 3^3$$

$$= 3 \times 3 \times 3 = 27$$

Therefore, $$27$$ is the cube number of $$3$$.
The following table consist of cube numbers of the first ten numbers.

 Number Cube number Number Cube number 1 $$1^3 = 1$$ 11 $$11^3 = 1331$$ 2 $$2^3 = 8$$ 12 $$12^3 = 1728$$ 3 $$3^3 = 27$$ 13 $$13^3 = 2197$$ 4 $$4^3 = 64$$ 14 $$14^3 = 2744$$ 5 $$5^3 = 125$$ 15 $$15^3 = 3375$$ 6 $$6^3 = 216$$ 16 $$16^3 = 4096$$ 7 $$7^3 = 343$$ 17 $$17^3 = 4913$$ 8 $$8^3 = 512$$ 18 $$18^3 = 5832$$ 9 $$9^3 = 729$$ 19 $$19^3 = 6859$$ 10 $$10^3 = 1000$$ 20 $$20^3 = 8000$$