Question

How many numbers are there containing two digits?

Answer 1

Finding numbers contains two digit:

Formula for finding numbers contain two digit is $(Greatesttwodigitnumber-smallesttwodigitnumber)+1$

$\therefore$Greatest $2$ digit number is $99$ and smallest is $10$

Substitute values in the formula
$$\begin{gathered} \Rightarrow (99-10)+1 \\ \Rightarrow 89+1=90 \end{gathered}$$

Hence, there are $90$ numbers containing two digits.