What is x when 13 divided by x equals 21?

To find the answer, just divide the dividend by the quotient: 13 ÷ 21 = 0.61904761904762

To prove this, let's compute 13 divided by 0.61904761904762: $\frac{13}{0.61904761904762} = 21$

How does it work?

Asking what the value of x could be when 13 divided by x gives a result of 21, is equivalent to solving the following equation:

$\frac{13}{x} = 21$

Multiply both sides by x: $\frac{13 x}{x} = 21 x$
$\frac{13 x}{x}$ is equivalent to $\frac{x}{x} \times 13$ , which simplifies to $1 \times 13$ (or just $13$ ).
Thus, the equation becomes: $13 = 21 x$
To find x, divide both sides by 21: $\frac{13}{21} = \frac{21 x}{21}$
Which gives, after simplification: $0.61904761904762 = x$ (or $x = 0.61904761904762$ )

So, if the dividend is 13 and the quotient is 21, the divisor is 0.61904761904762.