Question

When the expression 10^2021 − 2021 is evaluated, the result is a very large number.

You probably do not have enough time to perform the calculation. So, in an
effort to save you some time and paper, instead of evaluating the expression
10^2021 − 2021, determine the sum of the digits in the difference. How do I do this pls

Answer 1

18,176

Explanation:

Figure out an easier thing to do: 1000 - 2021 = 9,797.

Therefore, our answer will be like 9999999999999999999999997979. Out of all of these digits, there are only 2 that arent nines. We know the amount of digits since it's 10^2021 power. We will have one less since we are subtracting 2021. Therefore, 2020 digits in total. Now we know of those 2020 digits, 2 of them are 7, therefore 2018 of them are 9s. That means do 2018(9) + 2(7) = 14 + 18,162 = 18,176.