Correct Answer - Option 1 : 4

**Given:**

\(\sqrt {20 - \sqrt {20 - \sqrt {20 - \sqrt {20 - ...\infty } } } } \)

**Concept used:**

Simplification

**Calculation:**

Here 20 is given inside the root.

Break it into consecutive order

⇒ 4 × 5 = 20

In case of subtraction the smaller number will be the answer.

Here Ans : 4