How many digit required to write numbers from 1 to 50 ?

Answer: Option C

$$\begin{array}{rl}& \text{No}\text{. of digits}\\ & \text{0 - 9 }\to \text{ 1}\times \text{9 = 9}\\ & \text{10 - 19 }\to \text{ 2}\times \text{10 = 20}\\ & \text{20 - 29 }\to \text{ 2}\times \text{10 = 20}\\ & \text{30 - 39 }\to \text{ 2}\times \text{10 = 20}\\ & 40\text{ - 49 }\to \text{ 2}\times \text{10 = 20}\\ & 50\to 2\times \text{1 = 2 = 91}\end{array}$$