To find the number $x$ such that six and a half of that number equals 20, we can set up the equation as follows:

$\frac{13}{2} \times x = 20$

To solve for $x$, multiply both sides of the equation by $\frac{2}{13}$:

$x = \frac{20 \times 2}{13}$

$x = \frac{40}{13} \approx 3.08$

So, the number is approximately 3.08.

Would you like any more details or have any questions? Here are five related questions to explore further:

1. What is six and a half of 15?
2. If three times a number is 20, what is the number?
3. How do you calculate one-third of a number?
4. What is the decimal equivalent of 6 and a half?
5. How can you solve equations involving fractions?

Tip: When solving equations involving fractions, it's often helpful to first multiply both sides by the denominator to eliminate the fraction.