GMAT Strategy

I believe I recall reading in the instructions to the GMAT that you cannot take a watch into the exam. Is this correct? If so, how does everyone keep time down to the second?

There's a digital clock on the computer screen.

Does the clock count up or down? If it counts up, then it's easy to keep track of how many questions you should have completed based on the question number and elapsed time. If it counts down, it's not so easy.

It counts down. I usually just approximated how much time I had remaining quickly in my head. Some people prefer to write down the time guide below. Lefthand number is the question number; righthand number is minutes remaining.

Q: 5:66, 10:56, 15:46, 20:36, 25:26, 30:16, 35:6
V: 5:67, 10:58, 15:49, 20:40, 25:31, 30:22, 35:13, 40:4