Let the total number of candidates be $x$.
Let the number of successful candidates be $y$.

The percentage of successful candidates is 75.6%.
Write this as a fraction[1]:

$$\frac{y}{x} = \frac{75.6}{100}$$

Simplify the fraction:

$$\frac{y}{x} = \frac{756}{1000}$$

For the least number of candidates, we need to find the smallest possible values for $x$ and $y$ that satisfy the equation.

Find the greatest common divisor (GCD) of the numerator and denominator of the fraction:

$$\text{GCD}(756, 1000) = 4$$

Divide both the numerator and denominator by the GCD:

$$\frac{y}{x} = \frac{(756/4)}{(1000/4)}$$

$$\frac{y}{x} = \frac{189}{250}$$

From the simplified fraction, we can see that the least number of candidates $x$ is 250, and the least number of successful candidates $y$ is 189.

The least possible number of candidates in the examination is 250.