Radical 囗
5 strokes
enclosed 囗 (24a) + boy 儿 (21) = four 四
We have now met several numbers — the other numbers up to ten follow shortly, in Chapter 4.


The kidnapped boy was enclosed by the force-field on all four sides. / The dwarf, leading the rescue team, saluted when they found him (perhaps because he was the colonel’s son).

This is like mouth, only bigger! You can always tell them apart as “mouth” never has anything inside it, whereas “enclosed” always does.
You always delay writing the final stroke of “enclosed” until after the contents have been drawn in. The next character demonstrates this rule in action.