The Integrated Reasoning section does not contribute to the total 200–800 GMAT score. Instead, it’s scored on its own scale from 1 to 8, in whole-point increments. Since there are 12 items on the IR section, there is not a one-to-one correspondence between the number of items you get right and your score on the section. This is at least in part due to the presence of some unscored experimental items. However, since you will not know which items are experimental, you should treat every item as though it counts.
While a few items in the IR section are traditional multiple-choice questions, most items require two or three selections. There is no partial credit. Thus, getting two questions right and one question wrong on a three-part Table Analysis or Multi-Source Reasoning item is exactly the same as getting all three questions wrong. For more information about scoring, see Chapter 1: Introduction to the GMAT.