Study the pattern and solve it by giving an explanation.
We have to study the pattern first and then solve the last part based on that pattern.
In the first case,
The sum of all numbers written in
Now, we observe that,
product of digits sum of digits.
Similarly on the same pattern in the second case,
The sum of numbers,
Now, in , the sum of digits product of digits
So, by using same pattern, in the third case , we have
Sum of numbers
Now, sum of digits product of digits .
Hence, the required answer is .