Question

Difference of the greatest $7$ digits number and the smallest $5$ digits number is
(A) $998999$
(B) $9989999$
(C) $99899$
(D) $998099$

Answer 1

Hint: Firstly, we have to write the greatest $7$ digits number and then the smallest $5$ digits number. then we have to find their difference to get the required result.

Complete step-by-step answer:
The greatest seven digits natural number is \[9999999\].
The smallest $5$ digits natural number is $10000$.
Now, we have to calculate the difference of the largest $7$ digits natural number and the smallest $5$ digits natural number.
The required difference is $9999999 - 10000 = 9989999$.
Thus, the difference of the greatest $7$ digits number and the smallest $5$ digits number is $9989999$.

Hence, option (B) is correct.

Note:
The difference of the greatest $7$ digits natural number and the smallest $5$ digits natural number can be calculated by column method. In this method the greatest $7$ digits number is written in row and the smallest five digits number is written in below rows and then subtracted column-wise. that is,
 $
  9999999 \\
 \underline {-\,\,\,\,10000} \\
  9989999 \\
 $
The difference of the greatest $7$ digits natural number and the smallest $5$ digits natural number can also be calculated by using the concept of Vedic mathematics. In this concept our basic aim is to convert the given numbers into numbers having maximum number of zero either by adding or subtracting a small number and then we have to perform the required operation. In the above cases we can add one to the greatest seven digits natural number as it gives a number having seven zeroes and then subtract the smallest five digits number and finally subtract one to get the required result.