The total amount of us currency in circulation divided by the us population comes out to about $3,500 per person. that is more than most of us carry. where is all the cash?

Some of the money is stored in banks - those are called reserves. Banks usually keep a portion of the money that people deposited in their reserves.

Additionally, some cash is in the cash register - every cash register has some money to be able to give people change - so this is money owed by companies, and not by private people

You can drink laxative, or  do this exercise when you are sitting in the bathroom on the toilet. to relieve  constipation  fast or in about 1 minute, pinch your nose after your usual exhalation. start holding your breath. but do not mouth breath during this just hold your breath. 

South central region