Difference of greatest three digits number and smallest five digits number is:
A.19001
B.9011
C.9001
D.9091

Hint: First of all we should find the greatest 3 digit number and the smallest 5 digit number and then we can find the difference by subtracting the 3 digit number from the 5 digit number.

Complete step-by-step answer:

So, let us find the greatest 3 digit number.
Since, we know that 9 is the greatest single digit number. So, when we have to form the greatest 3 digit number we can simply write three 9 together. It gives us the greatest 3 digit number as 999.
Now, we will find the smallest 5 digit number.
We all know that the smallest single digit number is 0, but writing five times 0 together means but only 0.
So, in this case we will take a single digit number which is just greater than zero and we will use that number as the first digit and 0 as the other 4 digits.
So, 1 is the single digit number which is just greater than 0. So, we will use 1 as the 1st digit and 0 to the other 4 digits for the smallest five digit number.
Therefore, the smallest 5 digit number is 10000.
Now to get the difference between these two numbers we will subtract the smaller number from the greater one. So, here the smaller number is 999 and 1000 is the greater one.
Therefore, difference = 10000-999
                                        = 9001
Therefore, the difference between the greatest 3 digit number and smallest five digit number is 9001.
Hence, option (c) is the correct answer.

Note: Students should be careful while finding the greatest 3 digit number and the smallest 5 digit number and for the 5 digit smallest number taking only 0 or only 1 at all the 5 places will be a mistake.