**September 1, 2019, | **

Often we can't imagine how many small onions we should cut instead of the big one.
Luckily, we can calculate this using a simple three-dimensional sphere volume formula.
Suppose we have a large onion that has each of 3 dimensions twice the size of the small one.
If the radius r is, for example, 2 cm, then the radius of the large onion 2r is 4 cm.
The volume of a large sphere is always 8 times greater than the volume of a sphere with a half radius r.

**V**_{1}:

Volume of sphere / large onion

**V**_{2}:

Volume of sphere / small onion

**r**_{1}: 2r

- Radius of a large onion

**r**_{2}: r

- Radius of a small onion

**π: 3,14**

- Ludolf's number