What is x when 40 divided by x equals 4?

To find the answer, just divide the dividend by the quotient: 40 ÷ 4 = 10

To prove this, let's compute 40 divided by 10: $\frac{40}{10} = 4$

How does it work?

Asking what the value of x could be when 40 divided by x gives a result of 4, is equivalent to solving the following equation:

$\frac{40}{x} = 4$

Multiply both sides by x: $\frac{40 x}{x} = 4 x$
$\frac{40 x}{x}$ is equivalent to $\frac{x}{x} \times 40$ , which simplifies to $1 \times 40$ (or just $40$ ).
Thus, the equation becomes: $40 = 4 x$
To find x, divide both sides by 4: $\frac{40}{4} = \frac{4 x}{4}$
Which gives, after simplification: $10 = x$ (or $x = 10$ )

So, if the dividend is 40 and the quotient is 4, the divisor is 10.