What is x when 81 divided by x equals 8?

To find the answer, just divide the dividend by the quotient: 81 ÷ 8 = 10.125

To prove this, let's compute 81 divided by 10.125: $\frac{81}{10.125} = 8$

How does it work?

Asking what the value of x could be when 81 divided by x gives a result of 8, is equivalent to solving the following equation:

$\frac{81}{x} = 8$

Multiply both sides by x: $\frac{81 x}{x} = 8 x$
$\frac{81 x}{x}$ is equivalent to $\frac{x}{x} \times 81$ , which simplifies to $1 \times 81$ (or just $81$ ).
Thus, the equation becomes: $81 = 8 x$
To find x, divide both sides by 8: $\frac{81}{8} = \frac{8 x}{8}$
Which gives, after simplification: $10.125 = x$ (or $x = 10.125$ )

So, if the dividend is 81 and the quotient is 8, the divisor is 10.125.