"Quad" means "four", thus:
- In those countries that use the long scale (based on powers of million) like Europe:
quadrillion = millionfour = (106)4 = 1024
so a quadrillion is 10 to the power of 24.
- In those countries that use the short scale (based on powers of thousand) like USA:
quadrillion = thousandfive = (103)(4+1) = 1015
so a quadrillion is 10 to the power of 15.
