Convert UK gallon to US beer barrel
Unit definitions
UK gallon
The UK gallon is a unit of volume equal to exactly $4.546\,09$ liters.
US beer barrel
The US beer barrel is defined as exactly $31$ US liquid gallons.
How to convert UK gallon to US beer barrel
$$\text{Volume}_{\text{bbl (beer)}} = \text{Volume}_{\text{gal (uk)}} \cdot 0.03874032017757596547336803982671605$$
Examples
Example 1
Convert $50.0\ \text{gal (uk)}$ to $\text{bbl (beer)}$.
$$\text{Volume}_{\text{bbl (beer)}} = 50.0 \cdot 0.03874032017757596547336803982671605$$
$$\text{Volume}_{\text{bbl (beer)}} = 1.937016$$
$$\therefore \ 50.0\ \text{gal (uk)} = 1.937016 \ \text{bbl (beer)}$$
Example 2
Convert $70.0\ \text{gal (uk)}$ to $\text{bbl (beer)}$.
$$\text{Volume}_{\text{bbl (beer)}} = 70.0 \cdot 0.03874032017757596547336803982671605$$
$$\text{Volume}_{\text{bbl (beer)}} = 2.711822$$
$$\therefore \ 70.0\ \text{gal (uk)} = 2.711822 \ \text{bbl (beer)}$$
Example 3
Convert $120.0\ \text{gal (uk)}$ to $\text{bbl (beer)}$.
$$\text{Volume}_{\text{bbl (beer)}} = 120.0 \cdot 0.03874032017757596547336803982671605$$
$$\text{Volume}_{\text{bbl (beer)}} = 4.648838$$
$$\therefore \ 120.0\ \text{gal (uk)} = 4.648838 \ \text{bbl (beer)}$$
Example 4
Convert $135.0\ \text{gal (uk)}$ to $\text{bbl (beer)}$.
$$\text{Volume}_{\text{bbl (beer)}} = 135.0 \cdot 0.03874032017757596547336803982671605$$
$$\text{Volume}_{\text{bbl (beer)}} = 5.229943$$
$$\therefore \ 135.0\ \text{gal (uk)} = 5.229943 \ \text{bbl (beer)}$$
Example 5
Convert $175.0\ \text{gal (uk)}$ to $\text{bbl (beer)}$.
$$\text{Volume}_{\text{bbl (beer)}} = 175.0 \cdot 0.03874032017757596547336803982671605$$
$$\text{Volume}_{\text{bbl (beer)}} = 6.779556$$
$$\therefore \ 175.0\ \text{gal (uk)} = 6.779556 \ \text{bbl (beer)}$$