noun
each; per piece
Used when specifying a quantity, price, or attribute for each individual item. Common in commercial and instructional contexts.
このリンゴは一個当たり百円です。
These apples are 100 yen each.
一個当たりの重さを量ってください。
Please weigh each piece.
Compound of 一個 (one piece) and 当たり (per, hit). The reading いっこ is a standard counter form of 一個.