Other forms: quadrillions
It's a little time consuming to write out the number one quadrillion, since it's a one and fifteen zeros.
It's probably a good time to brush up on big numbers, now that billions and even trillions are bandied about as if they were mere dozens. A quadrillion is one followed by fifteen zeroes. If you're looking for a mnemonic, the root word, quad, "four" from the Latin quadri, refers to the number of groups of three zeroes that follow one thousand.