What is x when 21 divided by x equals 66?

To find the answer, just divide the dividend by the quotient: 21 ÷ 66 = 0.31818181818182

To prove this, let's compute 21 divided by 0.31818181818182: $\frac{21}{0.31818181818182} = 66$

How does it work?

Asking what the value of x could be when 21 divided by x gives a result of 66, is equivalent to solving the following equation:

$\frac{21}{x} = 66$

Multiply both sides by x: $\frac{21 x}{x} = 66 x$
$\frac{21 x}{x}$ is equivalent to $\frac{x}{x} \times 21$ , which simplifies to $1 \times 21$ (or just $21$ ).
Thus, the equation becomes: $21 = 66 x$
To find x, divide both sides by 66: $\frac{21}{66} = \frac{66 x}{66}$
Which gives, after simplification: $0.31818181818182 = x$ (or $x = 0.31818181818182$ )

So, if the dividend is 21 and the quotient is 66, the divisor is 0.31818181818182.