Solve the programming task below in a Python markdown code block.
My grandfather always predicted how old people would get, and right before he passed away he revealed his secret!

In honor of my grandfather's memory we will write a function using his formula!

* Take a list of ages when each of your great-grandparent died.  
* Multiply each number by itself.  
* Add them all together.  
* Take the square root of the result.  
* Divide by two.

## Example

```R
predict_age(65, 60, 75, 55, 60, 63, 64, 45) == 86
```
```python
predict_age(65, 60, 75, 55, 60, 63, 64, 45) == 86
```

Note: the result should be rounded down to the nearest integer.

Some random tests might fail due to a bug in the JavaScript implementation. Simply resubmit if that happens to you.
Also feel free to reuse/extend the following starter code:
```python
def predict_age(age_1, age_2, age_3, age_4, age_5, age_6, age_7, age_8):
```