North Carolina General Contractors Practice Exam 2026 - Free Contractors Practice Questions and Study Guide

The second method for checking the squareness of a slab is known as the 6-8-10 rule. This method is a variation of the more commonly referenced 3-4-5 rule, which utilizes a right triangle where the lengths of the sides maintain a ratio that demonstrates a right angle. The 6-8-10 rule operates on the same principle; it still forms a right triangle but uses different dimensions.

In this context, if you have a rectangle or slab and you want to ensure that the corners are square (meaning they are right angles), you can measure out 6 units along one side, 8 units along the adjacent side, and then measure the diagonal to ensure it is exactly 10 units. If this measurement holds true, you can confirm that the angles are square. This method can be particularly useful for larger areas, as the lengths used provide more accurate measurements compared to shorter ones.

Both the 3-4-5 and 6-8-10 rules are practical applications of the Pythagorean theorem, confirming the integrity of right angles. However, when specifically referring to this second method, the 6-8-10 rule is the correct terminology, making it the right choice here.