数十亿

• 娄(many times; piled up)PHONO-SEMANTIC
• 攵(tap; hand motion)RADICAL

Counting numbers is using your hand to tap repeatedly many times in order to calculate.

• 十(number ten; cross shape)ASSOCIATIVE

Two intersecting strokes form a complete whole, symbolizing the number ten.

• 亻(person; human; people)RADICAL
• 乙(second (heavenly stem; earthly branch))PHONETIC

Billions of people in the world, crowded like ants, line up from the first to the twelfth heavenly stem without end.