```
Ans = 7
```

To find out how.

```
Step 1: Separate the given table as column.
Step 2: Take each column. Separate the number as (top_number, middle_number, bottom_number)
Step 3: Put this formula for each column,
<bottom_number = (top_number + middle_number) / 2>
(6 + 4) / 2 = 5 (1st column)
(9 + 5) / 2 = 7 (2nd column)
(2 + 4) / 2 = 3 (3rd column)
(7 + 1) / 2 = 4 (4th column)
(8 + 6) / 2 = 7 (5th column)
```