What is x when 64 divided by x equals 21?

To find the answer, just divide the dividend by the quotient: 64 ÷ 21 = 3.047619047619

To prove this, let's compute 64 divided by 3.047619047619: $\frac{64}{3.047619047619} = 21$

How does it work?

Asking what the value of x could be when 64 divided by x gives a result of 21, is equivalent to solving the following equation:

$\frac{64}{x} = 21$

Multiply both sides by x: $\frac{64 x}{x} = 21 x$
$\frac{64 x}{x}$ is equivalent to $\frac{x}{x} \times 64$ , which simplifies to $1 \times 64$ (or just $64$ ).
Thus, the equation becomes: $64 = 21 x$
To find x, divide both sides by 21: $\frac{64}{21} = \frac{21 x}{21}$
Which gives, after simplification: $3.047619047619 = x$ (or $x = 3.047619047619$ )

So, if the dividend is 64 and the quotient is 21, the divisor is 3.047619047619.