No matter where you are, you can use this. When you feel yourself getting caught up in the "Tilt-a-Whirl" of an attack, calculate something. If you are driving, look at a license plate in front of you, look at gas prices, catch a glimpse of a realtor's number.
Add them together, multiply the number by 2, subtract one half of the number by the other half. Whatever.
This has helped me many times. How it works: It serves to disconnect the part of your brain that is experiencing the panic/anxiety attack (amygdala and the limbic system) and connects with the parietal lobe of the brain that has to do with spatial reasoning.
It's like short-circuiting the thought process.