What are the different graduations seen on rules? The specific markings on the measurement tool itself that evenly divide up the space of the scale are called graduations. These markings are typically straight when found on a rule, but may also be curved, like in the case of a protractor. When using a rule, you will want first to make sure that the graduations are appropriate for the type of measurement are you doing. You will need a rule with different gradations when your measurement requires more finite increments than when you are getting a rough estimate of a length. The common naming system for graduations uses different numbers and letters to distinguish the measurement capabilities such as 3R, 4R, 9R, and others. The different names signify the length of the measurement increments that can be found on that particular rule. For example, a 3R rule measures in 10ths and 50ths on the front and 64ths and 32nds on the back, a 4R rule measures in 8ths and 16ths on the front and 64ths and 32nds on the back, and a 9R rule measures in 16ths and 32nds on the front and 64ths on the back.