To convert the decimal \(0.264\) to a rational number, you would set the number equal to a variable, typically \(x\):
\[ x = 0.264 \]
To eliminate the decimal, you can multiply both sides by \(1000\) (since there are three digits after the decimal point):
\[ 1000x = 264 \]
Now, you can express \(x\) as a rational number:
\[ x = \frac{264}{1000} \]
You can simplify this fraction if needed, but to answer your question directly, the number you would multiply both sides by is \(1000\).