密度计

• 宓(quiet; hidden)PHONETIC
• 山(mountain (pictograph))ASSOCIATIVE

A secluded place like a mountain surrounded and concealed hides all secrets.

• 广(roof; broad eaves)RADICAL
• 廿(twenty; many times measure)ASSOCIATIVE
• 又(right hand; again; once more)ASSOCIATIVE

Under a roof, use your hand to measure back and forth many times to get accuracy.

• 言(word; speech)RADICAL
• 十(ten)PHONETIC

Calculation is using words to count numbers one by one.