Question

how many 8 digit number are there in all

Answer 1

1)if it's only positive integer

Let's see, the smallest 8 digit number is 10,000,000 and the largest is 99,999,999

so the total number of 8 digit numbers is

9,99,99,999 - 1,00,00,000 + 1 = 9,00,00,000


2)if its positive and negative both

Let's see,multiply the above answer by two because the no. of positive numbers and negative numbers are same

9,00,00,000 × 2 = 180,000,000