Origin

The character 億 combines a person classifier on the left with 意, which provides a sound hint for how to pronounce it (roughly "o" sound). In Chinese, this character was created to represent the enormous number hundred million by pairing a human-related radical with a phonetic component. The person classifier likely suggests the idea of counting or reckoning something so vast that only humans would need to track it, while the right side tells you how to say the word aloud. Over time, the character became the standard way to write this large numerical unit in both Chinese and Japanese.