Literature Reference: May the blessings of hundreds of millions be dedicated to Emperor Yao for thousands of years. Source from 'Fenghe Lindianyan Bailiao Yingzhi'.
亿: "亿万" refers to a number, specifically one hundred million (a "wan" being ten thousand, and "yi" being ten thousand times that), though in ancient times it denoted one hundred thousand. It generally signifies an immense quantity, symbolizing wealth and prosperity, and carries the implication of hoping to attain a life of glory, riches, and honor.
兆: Auspicious sign. This character, when used in personal names, brings great fortune.
Meaning: Billions signify immense prosperity and boundless blessings.