Answer: The sum of the digits of 99 × n is 27 - 10 = 17.
Explanation:
To find the sum of the digits of 99 × n, we can use the fact that 99 × n = 100 × n - n. The sum of the digits of 100 × n is simply n, since the hundreds digit is zero. Therefore, the sum of the digits of 99 × n is equal to the sum of the digits of n - n, which is simply zero.
For example, if n = 37, then 99 × n = 99 × 37 = 3,699. The sum of the digits of 3,699 is 3 + 6 + 9 + 9 = 27. The sum of the digits of 37 is 3 + 7 = 10. Therefore, the sum of the digits of 99 × n is 27 - 10 = 17.