What is x when 81 divided by x equals 51?

To find the answer, just divide the dividend by the quotient: 81 ÷ 51 = 1.5882352941176

To prove this, let's compute 81 divided by 1.5882352941176: $\frac{81}{1.5882352941176} = 51$

How does it work?

Asking what the value of x could be when 81 divided by x gives a result of 51, is equivalent to solving the following equation:

$\frac{81}{x} = 51$

Multiply both sides by x: $\frac{81 x}{x} = 51 x$
$\frac{81 x}{x}$ is equivalent to $\frac{x}{x} \times 81$ , which simplifies to $1 \times 81$ (or just $81$ ).
Thus, the equation becomes: $81 = 51 x$
To find x, divide both sides by 51: $\frac{81}{51} = \frac{51 x}{51}$
Which gives, after simplification: $1.5882352941176 = x$ (or $x = 1.5882352941176$ )

So, if the dividend is 81 and the quotient is 51, the divisor is 1.5882352941176.