In states that allow an Ugly's book bring it. I found the tables very useful and quicker to get to then the tables in the code book. Specifically you will see questions on FULL-LOAD CURRENT IN AMPERES, DIRECT CURRENT MOTORS, ELECTRICAL FORMULAS FOR CALCULATING AMPERES, HORSEPOWER, KILOWATTS AND KVA, OHMS LAW, SERIES CIRCUITS, PARALLEL CIRCUITS.
Even if your state does not allow this book in the testing area it is a great reference for all the calculations on the test. You can use it as you go through the test which will get you back into doing calculations.
This book is your bible on the job. You will open it more than your code book especially when your bending pipe or finding a quick wire size or conduit fill. Here is my affiliate link so you can hook yourself up.