If all the $6$ are replaced by $9$, then the algebraic sum of all the numbers from $$1 to $100$ (both inclusive) varies by?
Question - What is the difference between algebraic sum of numbers(with $6$ and when $6$ is replaced by $9$)?
Answer - Answer is $330$
I can do it manually but in exam time is limited and it take time to add these numbers, So I want to know that how can I solve it quickly and what if the range is big like $1$ to $1000$ how to solve it quickly?