To divide a number by a fraction, you can multiply the number by the reciprocal of that fraction.
In this case, you have:
\[ 6 \div \frac{1}{3} \]
This is the same as:
\[ 6 \times \frac{3}{1} \]
Now, calculating that gives:
\[ 6 \times 3 = 18 \]
So, \( 6 \div \frac{1}{3} = 18 \).