Texas Land Units: Varas and Leagues

Texas surveying units show up on every UIL paper, usually as a starred problem. Two constants carry all of them.

A vara is $33\frac{1}{3}$ inches, which is exactly $\frac{25}{27}$ of a yard. So varas to yards is a multiplication by $\frac{25}{27}$ — near enough to $0.926$ that you can estimate by subtracting about $7.4\%$.

A league of land is $4{,}428.4$ acres. A labor is $177.1$ acres, and a league is exactly $25$ labors.

Because these are starred, you only need to land within $5\%$ — round the constant aggressively and move on.