Find the sum of all the digits of the result of the subtraction 1099−99.
1099 has ninety nine 0 and one 1
On subtracting 99 , we'll get a number with ninety seven 9 and ending with 01
1099−99=99...9997 times01
Sum of all digits of this number =(97×9)+(1×0)+(1×1)=874