We breath a lot of air each day. Just say we breath 17280 times, which, if each breath includes 1000 molecules of air, then we use about 1.7x10^7 molecules of O2/day.
Small number would be like the size of a dust mite crawling around. Say it's 4.6x10^-6 meters in width.
Small number would be like the size of a dust mite crawling around. Say it's 4.6x10^-6 meters in width.