One day, River writes down the numbers 1, 2,, 999 What is the sum of all the digits that River wrote down? And what is the number of all the digits River wrote down

He wrote down 999 digits and the sum is

499,500

Step-by-step explanation:

1+2+3 going all they up to 999 and then added together.

c.

step-by-step explanation:

simple you would first have to get   a negative number where as 1 to be multiplied by 24 and then you would have to multiply 6 time 4 and then repeat that process until you reach your term