Forerunner numbers

"However, the desperate war against the Flood allowed for no beauty, no elegance, only the music produced by lances of crystalized light and the brilliance of burning mountains of corrupted flesh. No songs were sung by these Warrior-Servants of bravery, of victory, of hopes for a tomorrow. There was no tactical finesse to be wielded against the infection, no favor or promise that could turn the Gravemind from its purpose, no stratagem that could withstand its cold calculation. As millions of dead Forerunner warriors turned into billions, then trillions, the wicked and graceful weapons and armors of the old Forerunner guardians were ground into the dirt, crushed underfoot, and then erased from all memory with the unravelling of the Domain. All that followed were sterile, efficient instruments of death without any beauty. In the desperate fight against the Flood there was only time for survival and duty, not art." (Halo Waypoint; Uncharted Waters)