A number exceeds 20% of itself by 40. Find the number.

Let the required number be x.

20% of the number = $\dfrac{20}{100}x = \dfrac{1}{5}x$

According to the question x exceeds 20% of itself by 40:

$\therefore x - \dfrac{1}{5}x = 40 \\[1em] \Rightarrow \dfrac{5x - x}{5} = 40 \\[1em] \Rightarrow \dfrac{4x}{5} = 40 \\[1em] \Rightarrow 4x = 40 \times 5 \\[1em] \Rightarrow 4x = 200 \\[1em] \Rightarrow x = \dfrac{200}{4} \\[1em] \Rightarrow x = 50$

Hence, the required number is 50.