Question

How many $6-\mathrm{digit}$ numbers are there in all?

Answer 1

We know that

Largest $6-\mathrm{digit}$ number $=9,99,999$

Smallest $6-\mathrm{digit}$ number $=1,00,000$

The number of $6-\mathrm{digit}$ numbers are $=$largest number $-$ smallest number $+1$

$$\begin{gathered} =9,99,999-1,00,000+1 \\ =8,99,999+1 \\ =9,00,000 \end{gathered}$$

Hence the total number of $6-\mathrm{digit}$ numbers are $9,00,000$