What is x when 81 divided by x equals 10?

To find the answer, just divide the dividend by the quotient: 81 ÷ 10 = 8.1

To prove this, let's compute 81 divided by 8.1: $\frac{81}{8.1} = 10$

How does it work?

Asking what the value of x could be when 81 divided by x gives a result of 10, is equivalent to solving the following equation:

$\frac{81}{x} = 10$

Multiply both sides by x: $\frac{81 x}{x} = 10 x$
$\frac{81 x}{x}$ is equivalent to $\frac{x}{x} \times 81$ , which simplifies to $1 \times 81$ (or just $81$ ).
Thus, the equation becomes: $81 = 10 x$
To find x, divide both sides by 10: $\frac{81}{10} = \frac{10 x}{10}$
Which gives, after simplification: $8.1 = x$ (or $x = 8.1$ )

So, if the dividend is 81 and the quotient is 10, the divisor is 8.1.