Evaluate the
`sqrt(20-sqrt(16))`

Answer

To evaluate the expression \( \sqrt{20 - \sqrt{16}} \), we will follow these steps:

### Step 1: Identify the expression
We start with the expression:
\[ \sqrt{20 - \sqrt{16}} \]

### Step 2: Calculate \( \sqrt{16} \)
Next, we need to evaluate \( \sqrt{16} \):
\[ \sqrt{16} = 4 \]

### Step 3: Substitute back into the expression
Now, we substitute \( \sqrt{16} \) back into the expression:
\[ \sqrt{20 - 4} \]

### Step 4: Simplify the expression inside the square root
Now we simplify \( 20 - 4 \):
\[ 20 - 4 = 16 \]

### Step 5: Calculate \( \sqrt{16} \)
Finally, we calculate \( \sqrt{16} \):
\[ \sqrt{16} = 4 \]

### Final Answer
Thus, the value of \( \sqrt{20 - \sqrt{16}} \) is:
\[ \boxed{4} \]