According to the French notation, which is followed also upon the Continent and in the United States, a unit with fifteen ciphers annexed; according to the English notation, the number produced by involving a million to the fourth power, or the number represented by a unit with twenty-four ciphers annexed. See the Note under Numeration.

(4) A digit(s) followed by 15 whole-number places. Quadrillion written in number form is 1,000,000,000,000,000 or in exponential form 1015.

the number that is represented as a one followed by 24 zeros; "in England they call a septillion a quadrillion"

A square cut diamond with 96 facets: 49 brilliant-style, 21 crown and 24 pavilion.

One thousand trillion.