When 636 is subtracted from a number, it reduces to its two–fifth. Which of the following would be twice that number?

Let's denote the unknown number as $x$.

According to the problem, when 636 is subtracted from $x$, the result is two-fifths of $x$. This can be written as: $x - 636 = \frac{2}{5}x$

To solve for $x$, we first isolate $x$ on one side of the equation. Start by eliminating the fraction by multiplying both sides by 5: $5(x - 636) = 2x$

Distribute the 5 on the left side: $5x - 3180 = 2x$

Next, move all terms involving $x$ to one side by subtracting $2x$ from both sides: $5x - 2x - 3180 = 0$ $3x - 3180 = 0$

Now, solve for $x$ by adding 3180 to both sides: $3x = 3180$

Finally, divide both sides by 3: $x = 1060$

The problem asks for twice that number, so we calculate: $2 \times 1060 = 2120$

Therefore, the answer is: $2120$