Question

The smallest 7- digit number is
A.10,00,000
B.1+ greatest 6-digit number
C.Either A or B
D.None of these

Answer 1

Hint: We have to find the number which should be of 7 digits and also it should be the smallest 7-digit number. For the smallest 7-digit number, we have to get just the successor of the greatest 6-digit number. The greatest 6-digit number is 9,99,999. Now, solve it further.

Complete step-by-step answer:
According to the question, we have to find the number which should have 7 digits and also it should be the smallest 7-digit number.
For finding the smallest 7-digit number, first of all, we have to find the greatest 6-digit number.
The greatest 6-digit number should contain 9 at all the six digits. So, the greatest 6-digit number is 9,99,999.
Greatest 6-digit number = 9,99,999 ………………..(1)
For the smallest 7-digit number, we have to get just the successor of the greatest 6-digit number. For the successor of the greatest 6-digit number, we have to add 1 to the greatest 6-digit number.
Smallest 7-digit number= 1 + Greatest 6-digit number ……………….(2)
From equation (1), we have the greatest 6-digit number. Putting the value of the greatest 6-digit number in equation (2), we get
Smallest 7-digit number= 1 + Greatest 6-digit number = 1 + 9,99,999 = 10,00,000.
Hence, the smallest 7-digit number is 10,00,000.

Note: We can also solve this question with a trick. The trick is that if we have to get the smallest n-digit number then make all the digits zero and make the 1st digit as 1. Here, we have to find the smallest 7-digit number. Using this trick, we have to make all the digits ‘0’ and have to make the 1st digit as ‘1’. So, the smallest 7-digit number is 10,00,000.