入木三分

入 = 丿 + ㇏ : Mnemonic symbol: an enter key like on a computer keyboard.

There is a special area in the space station's bathroom (Ø4) which is filled with bananas (丿), but you have to hit an enter key (入) to enter (入). Rachel Rhinoceros (ru) uses a finger (㇏) to press the button and get access to the bananas.

木 = 八 + 十 : Mnemonic symbol: a Christmas tree.

Malte Monkey (mu) is setting up a Christmas tree (木) in the bathroom of the space station (Ø4). He decorates the tree with eight-balls (八) and puts a holy cross (十) at the top of the tree.

三 = 一 + 二 : Mnemonic symbol: a Cartesian coordinate system with three (三) axes.

Socrates (s-) is performing in front of the anthill (-an1). He created an electrical flute by attaching a large capacitor (二) to the flute (一), so that he can get the attention of all the ants. Moreover, he's balancing on a Cartesian coordinate system (三). Unfortunately, only three (三) ants stop to watch the performance.

分 = 八 + 刀 : Symbol for this character: A stopwatch (from the meaning "minute"). Frankenstein's monster (f) participates in the annual championship of chopping eight-balls (八) in front of the encampment ((e)n1). Using a cleaver (刀), he chops (kind of divides / separates (分)) as many eight-balls as he can in one minute (分).